The exchange get its own advantage, if to sey you have bitcoin for the exchange, the p2p na zero (0) fee, if to say you get bitcoin for noncustodial wallet with segwit address (for lower fee) and wan send to binance, you still fit manipulate the feerate to one wey dey low and yet get your transaction put for block early, and zero p2p exchange for binance go make sense to exchange bitcoin for fiat.

The disadvantage be when you wan send bitcoin from binance, or when you buy (maybe through p2p) and wan send the bitcoin out of Binance. No dey advisable to send Bitcoin directly out of exchanges. Many payment companies dey accept altcoins like litecoin and ripple, you can use altcoins for low fee transaction.

And if to dey you wan transfer to you noncustododial wallet, the best na to send altcoin like litecoin to noncustodial exchanges, exchange to bitcoin back with low exchange fee into you desired wallet.

There are many different ways to buy Bitcoin:

1. It can be directly p2p which do not require any third party.
2. It can be through exchanges, but yet p2p
3. It can be through noncustododial decentralized exchanges like Bsiq which some people are using for privacy reasons
4.  It can be through normal exchanges

To know more about bitcoin transactions:
https://bitcointalk.org/index.php?topic=2848987.0
https://bitcointalk.org/index.php?topic=5309545.0
https://bitcointalk.org/index.php?topic=5320216.msg56441031#msg56441031

Or check this compilation
https://bitcointalk.org/index.php?topic=5319178.msg56412061#msg5641206

Exchange              Poll result

Binance                          9   

Remitano                       6

Paxful                             1

LocalBitcoins                1

Coincola

Blockvila

InstaShift

Coindirect

Redeeem

BuyCoins

Bsiq

CryptoLocally

Quidax

localcoinswap

Please, it will be good if we discuss about p2p exchanges this time around to avoid confusion, we hope one day we will be given local board, so we will be able to discuss more about bitcoin and many other cryptocurrencies our local board.

Please, select only three exchnges, if you think an additional one must be included, then you can select more than three exchanges, but give valid reasons why others exchnges are also selected along.

This will be a poll topic, but because we do not yet have a local board, I will be the one to count according to what we post, and post the result after one week. It starts today 6th of April, and it will end on 13th of April which is seven days from now.

These are the p2p exchanges that provide service for Nigerians. Which ones do you think are the best?
You can choose maximum of three exchanges.

Binance

Remitano

Paxful

LocalBitcoins

Coincola

Blockvila

InstaShift

Coindirect

Redeeem

BuyCoins

Bsiq

CryptoLocally

Quidax

localcoinswap

If you think there are some I have not yet mentioned, then you can post it so I can add it up here. Also, try to give reasons for the p2p exchnges you choose.

Note: There are scam dealers (scammers) while using p2p exchanges, make sure you directly check if you received bank payment directly from you bank account balance (not text messages from bank as text messages can be fake). Also, if you are the buyer, do not think twice to report to customer care if seller is not releasing bitcoin/other crypto from esrow after you have paid. And lastly, make sure you use your real account number corresponding to the name you used on the p2p exchange.

Spot trading is highly risky, leverage traiding is more risky, future type of leverage trading is riskiest. Trading is risky, not like the way you depicted it good. Especially, newbies in trading do lose while experienced traders still have some chances to still lose.

No. Learning is required.

To learn, it can be simple, but to make use of it to gain is hard. That is why some people like to hold than trade, because many people still lose while trading.

Binance will give you more. Check lists of exchanges according to their marketcap on Coinmarketcap, the ones at the top with highest marketcap have users that do lend for leverage trading, and these exchanges have more pairs. Especially Binance which is the first has more than 30 cryptocurrencies or more for future trading and many more for spot.

Whales use wallets to hold, noncustodial wallets preferably,  hardware and other offline wallets most preferably, while moving bitcoin from wallet to exchanges is indicating a bear market because the whales are moving bitcoin to exchanges to sell.

But, if whales are moving bitcoin from exchanges into wallet, it means they want to hold, and a sign bull market will soon begin.

I have just watched a video about Coinstar machine, and I think it will be good idea if bitcoin is supported also as part of the services provided. If the coins are to be used to collect the cash, 11.9% of the total worth of the coin will be deducted, bitcoin ATM deduct such a high fee also. So, if bitcoin is included, I do not think it will create any issue, and some people will like to make use of this if bitcoin is supported. I think all needed is to added bitcoin as as part of their service. As people are adopting bitcoin, there will be a time bitcoin will be supported, and it will really be useful for some people.

You are right, but it does not necessarily mean the hacker should have access to all the private key before the wallet will be compromised, it depends on the M of N multisig wallet that was created. Like in the 2 of 3 multisig wallet I explained above, the hacker only needs to know 2 out of the 3 private key to compromised the wallet, but in 2 of 2 multisig wallet, the hack needs all (the two) private key to compromise the wallet.

You mean if you lost one private key?

It depends, if it is 2 of 2 multisig wallet, you will not be able to access the fund again if you lost one private key. So, it depends on the numbers of cosigners. If you do not lost more than or exactly the number of co-signer private key, you will still be able to access your funds.

But, if you lost (public key), you can still use private key to regenerate public key. Private key is the one needed to not be lost.

Assuming you created 2 of 3 multisig. This means you have 2 cosigners out of 3 private keys in total. If an hacker was able to access one of the private keys, and unable to access the rest, there is nothing he can do, he can not brute-force the remaining two private keys. He must have access to at least two private keys in order to spend from the multisig wallet.

Private keys are used to access multisig wallets, the private keys can regenerate the public keys, so that is not an issue if you have the private keys. But, like in 2 of 3 multisig wallet, if you lost one private key, better move the bitcoin to a new multisig wallet. Also, if you notice any scam attempt, best to move the bitcoin to a new multisig wallet.

Some wallets do automatically rebroadcasting transactions, that is why it is good to make sure the wallet do not synchronize with the blockchain during the period. But, yet, some transactions will remain stuck in mempool for months. Because one of the above transactions has been dropped on blockchair.com, that does not mean it is not on other mempool. That is why it is good to just use replace-by-fee.

I think he meant he is sending the two unconfirmed transactions to Roobet, and nothing can be done than to wait.

He should still be able to use CPFP if the transactions have change address, but also not have change address, so he can not use it.

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Paid accelerator can be used, but the high fee will not let the OP use it. The only free acceleratator that is still working good which is ViaBTC can be used, but the transaction will at least have a feerate of 10 sat/vbyte.

The transaction do not support replace-by-fee, the second transaction has already been dropped from some mempool but that does not mean it is not still included on some other mempool. The first transaction has been rebrocasted which probably was automatically done by your wallet.

The thing is, if he sent the bitcoin to an exchange, there is nothing he can do. But, if he has the seed phrase or private key to the wallet, he can import it on electrum and use CPFP for the unconfirmed transaction.

Can you tell us if you have the seed phrase or the private key to the wallet you sent the bitcoin from? If you have it, or if the receiver has it, all needed to be done is for the receiver to send the whole unconfirmed bitcoin to another address on his wallet (this can required importing the seed phrase or private key to a wallet that can spend unconfirmed transactions, like electrum). But, a fee that will be able to confirm both the parent and child transactions at ones will be used for child transaction.

This transaction consists of 6 inputs and 1 output. Make sure the child transaction fee should be enough for 7 inputs and 2 outputs and substract the fee paid before from it

This transaction consist of 1 input and 1 output. Make sure the child transaction consist of fee that will confirm 2 inputs and 2 outputs after you substract the fee paid before from it.

So far the wallets mentioned above do not support private key importation, the best you can do is to still make use of electrum wallet.

First,
Get the private key of the address that the bitcoin is sent to on your electrum wallet.

Second,
Make use of Iancoleman.io offline, or the best if you download its HTML file offline and use. Check the Iancoleman site for the instruction on how to use it offline by scrolling down the site.

Input your BIP39 seed phrase
Make sure you know the address the funds are

Click on Derivation path BIP44 for legacy (addresses that start with 1), BIP49 for nested segwit addresses (addresses that start from 3) or BIP84 for native segwit (addresses that start with bc1), depending on the ones your funds are

Scroll down and you will seed the lists of addresses, check the ones that correspond (is the same) with the ones that store your bitcoin, scroll front to see the corresponding private key(s).

The private key of the address(es) that has the bitcoin on electrum, together with the ones that have the bitcoin on your BIP39 wallet, copy and paste all on a note pad in the format below

Address 1
Address 2
Address 3

Copy it, click on newly downloaded electrum wallet from electrum.org, verify its signature.

Open the wallet
Click on next
Click on import private keys or addresses
Paste the copied private key(s)
The click on next
Make the electrum wallet synchronize with the blockchain
The whole funds will appear
The you can transfer all to the wallet you want, or leave it till when you need it.

You can import seed phrase from BIP39 wallet to electrum, but you can not import electrum seed phrase to BIP39 wallets. But you can check for the private key of the addresses that have the fund,  and import the private key on BIP39 wallet. You can see the private key to an address under addresses on electrum wallet. But, I will not advice you to do that, 1 mBTC is 0.00001 BTC, that is a small amount. But if you insist, you will need to import the private key on the wallet of your choice that support private key importation.

Very possible a transaction can be so low to an extent it will not be able to be accelerated using free acceleratators, but some accelerators like ViaBTC still works, provided you still pay a fee that is not too low, and also making use of the acceleratator at earliest time of each hour, but not guaranteed that it would work. Most other free acceleratators will indicate the transaction has been acceleratated but nothing done and the transaction will still remain stuck.

Only people that have not tried out paid acceleratators will want to use it, and if about to be used, the fee that will be demanded for will make them to back off and not use it. A paid acceleratator can demand for $70 as fee for just want to make use of their service, even if the  transaction to be accelerated have low bitcoin amount. So, this is not a best option at all.

So far replace-by-fee can help so the amount paid as extra for fee to pump the transaction will be low, why no enable replace-by-fee for such transaction, so the fee can easily be pumped yet with low amount, instead of depending on free acceleratators or paid ones.

Another is child-pay-for-parent, it will be good to enable replace-by-fee, but child-pay-for-parent can be used if you still want to send bitcoin to another person, all you need to do is to spend from the change address from the previous (parent) transaction, so the both (parent and child) transactions will be confirmed at ones (although, the child transaction can also be an address on your wallet, but the fee will be higher than that of replace-by-fee), you need to use a fee that can get both (parent and child) transactions confirmed in a block fast in addition to the last paid fee.

Using 1 sat/vbyte could take months before it will be confirmed, it is not advisable for now. Even, using 5 sat/vbyte were luckily confirmed today since more than a month ago. Although, you can set such low fee if you want to consolidate your input, but make sure the transaction supoorts replace-by-fee, so you will be able to pump the fee in case of stuck transaction.

Assuming Mr A, B and C sent you 1 btc, 2 btc and 4 btc to your wallet address respectively, if you want to send the whole bitcoin to a friend, it will have 3 inputs, which are the number of times you received the whole btc you want to send irrespective of the number of addresses used to receive it. 1 output, because you send the whole btc to a friend and no change address.

Assuming you have 1 input, like only Mr A sent you 1.5 btc, if you want to send 1 btc to a friend, that means your wallet will send 1 btc to your friend and 0.5 btc to a change adddress (address on your wallet). This transaction have 1 input because you are sending btc from a transaction with a single received transaction (1.5 btc) from Mr A which can be used and remain change. 2 outputs because your wallet send to a friend and to a change address.

Transaction can remain in the mempool for months, especially if the wallet is synchronizing with the blockchain frequently, this will make the wallet to automatically rebroadcast the transaction. The best is to just enable replace-by-fee before broadcasting the transaction at all, so it can be used in case of stuck transaction. Normally, it is 14 days mempool might drop transactions, but possibly not all the mempools will drop it, while some will take it up as the wallet automatically rebroadcasting the transaction. There are cases of transactions that will remain stuck for months in mempool, and also are cases a dropped transaction will still be confirmed later, this second case is the reason people are advised to spend the same input if a transaction has been dropped from mempool. But, the best advice is to never think transaction will be dropped from mempool because it can be so frustrating if someone is experiencing stuck transaction that do not support replace-by-fee.

It will be good to make use of segwit addresses for payment, the fee paid will be lower if compared to legacy addresses, and the transaction fee will be in vbyte. 10 sat/vbyte is still a good fee especially during weekends, but you may need to increase the feerate during the weekdays as the mempool will be more congested. Just know that lowest fee are always during weekends, still lower further on Sundays.

What needed most is fee estimator. You can try mempool.space or mempool.observer. with such fee estimator, you can use it to set your feerate (sat/vbyte) on your wallet for more accurate estimation.

If the fee is too low, the transaction can be stuck, use mempool.space to set your fee. Or, you can use the estimators on wallets like electrum that runs good feerate estimation algorithm.

Normally, sweeping means to move the whole funds from wallets like paper wallet by proving the private key. Assuming, you have paper wallet, and you want to sweep to Wallet A. First of all, wallet A will have the sweeping feature, and it will request for private key of the paper wallet. Once you input the private key, the whole funds will be moved to the new wallet (wallet A). But, this is just a way you will have to just get your bitcoin to be handled by private key that will be online.

But what is explained above, you can send any amount of bitcoin you want (you can send half, you can send all, you can send less than half, or any amount), and yet your paper wallet private key is still offline, and yet the private key of the wallet you send it to is also offline. Nothing about your private key touch online. That is why I will strongly recommend the method.

From your second question, it is clear that Bob (the invader/hacker) do not know the same BIP38 password used to to encrypt both paper wallet.

The only way for Bob to know the unencrypted private key is if it is backup along with encrypted private key. But, why would Alice do that? Alice encrypted the private key on purpose, which is to provide another layer of protection.

If the unencrypted private key is known, it can be used to compromise the paper wallet.
If only the encrypted private key is known, it will be difficult for Bob to compromise/decrypt it if strong password is used.

If strong password is used, it will be difficult to brute-force the private key password

But, for additional security, using different BIP38 passphrase will be better.