Backup the seed on a couple pieces of laminated paper and you're fine
In case electrum ever seizes to exist, you can download the sourcecode of https://iancoleman.io/bip39/, open it on an offline machine, enter the seed and the correct derivation path, and you can derive as many private keys from your seed as you need... Afterwards you can import those keys into most reasonably decent wallets..

fabioganga gave the right reply on how to install the bitcoin core wallet on a linux machine, however, i'm unsure what you mean by "i am looking for ICO".

BTW: you do need to edit the download path, since this tutorial isn't for the very latest version of core...

The other option is to compile bitcoin core from source, the howto is actually described on the git repo: https://github.com/bitcoin/bitcoin/blob/master/doc/build-unix.md

No, it can be anywhere in the world, as long as the phone's time isn't wrong... You do know such a code only works for a couple of seconds, right?
If your phone's clock is off for 10 seconds, and the website's timestamp is wrong 5 seconds in the opposite direction, you only have a 15 second gap for your mom to tell you the code over the phone before it becomes invalid.

In that case, at this time, i'd recommand a fee of ~0.003, with this fee you'll have a very reasonable chance of getting your transaction confirmed within 2-3 hours.
If ~0.003 is to much (personally, i think it's a lot of money), you can always try a little lower fee, however you'll have to expect to wait a longer time.
A second option is to wait a couple of days and keep monitoring https://bitcoinfees.earn.com/ for a recommanded fee drop... There's a reasonable chance the recommanded fee might drop for shorter or longer periods over the next couple of weeks (not a guarantee tough).

no, it doesn't make a difference... An unspent output is an unspent output, disregarding which address it's funding.
As for your other question: if you have an idear which addresses are managed by your wallet, you can look those addresses up on a block explorer, even if you don't have physical access to your wallet.

For example: if you look up your address on blockchain.info, you should see a link called "Unspent Outputs". If you click it, you can count the number of unspent outputs funding this one address. If you do this for most (or all) of the funded addresses of your wallet, you know the number of unspent outputs (approximately... It's allways possible you're forgetting some addresses... And it's possible your wallet generated change addresses you don't know about to)

Like Alluro said, it can be done, however, you'd have to follow following steps:

1) open an account on a trusted exchange, generate a BTC deposit address
2) deposit BTC to the exchange... You'd still face a big tx fee when depositing your funds. The exchange might, or might not ask for a deposit fee
3) exchange BTC to an altcoin like ETH or LTC. The exchange allmost always asks for an exchange fee
4) withdraw your altcoin either directly to the receiver, or to your own altcoin wallet. You'll need to pay for a withdrawal fee which might or might not be higher than the actual miner's fee payed by the exchange

IF you want the altcoin to be converted back to BTC, you'll have to follow the procedure again, but now deposit the alt, exchange to btc and withdraw the btc.

As for your question wether it's profitable: it CAN be... If you're going to pay a lot of people, and they're accepting the altcoin in question, you might save a ton on transaction fees... Also, if the alt's price rises compared to BTC's price, you might be able to book a profit (keep in mind the relative price might also drop in comparison to bitcoins)... However, keep in mind that exchanging BTC to ALT's also costs extra transaction fees, deposit fees, withdrawal fees and exchange fees... So if those costs are higher than the potential profit, you're at a loss.
Also, exchanges can go bancrupt or turn scam pretty easily.

Theoretically, yes... If you were collecting 1000's of dust inputs, the fee can be really high when talking in fiat terms... However, if this is the case, let me know and i'll give you some tips on how to pay a smaller fee.

I was still editing my previous post (re-editing posts is something i like to do when i don't like my initial answer), i think your question has been answered by my edit.
In short: you'll be creating a transaction with x inputs and 1 output... To find the number of inputs, open your wallet ,go to help => debug window => console and type "listunspent" (without quotes offcourse). Now you can count the number of unspent outputs.
If you don't like the fee estimation bitcoin core is giving you, you can put the number of inputs you found by using the command "listunspent" and 1 output in my wizard: https://www.mocacinno.com/page/feeestimate (option 2)

Seems about right...
Now, to answer your questions:
You'd need to rescan the complete blockchain, but not redownload it. Rescanning can take a couple of hours, but everything depends on your cpu, memory and IO speed of your disk.
The best fee depends on the number of unspent outputs that are managed by your wallet (1). I wrote a tool long ago to help you with this task: https://www.mocacinno.com/page/feeestimate
If you have the number of inputs/outputs OR a list of funded addresses managed by your wallet, this tool will help you estimate a reasonable fee. However, if you keep your wallet open for a couple of hours before creating a tx, bitcoin core should have a reasonable fee estimation automatically.

As for your last question: there are ways to mess this up in a way you cannot fix it by having access to wallet.dat (1). However, as long as you keep 2 secure backups of both wallet.dat's, and you double check the deposit address generated by wallet.dat (2), i don't see a way to really mess things up.

I've actually given the correct answer in this very thread... It's not fixed, and it's not dependant on the value of the transferred BTC.
The fee depends on the size (in bytes), the size (in bytes) depends on the NUMBER of inputs and outputs, not on their value.

$33 for an average transaction seems a bit excessive.
https://bitcoinfees.earn.com/ teaches us that you'd need 380 sat/byte for a 95% chance of getting in the next 3 blocks. For an average, non-segwit, transaction of 226 bytes, that would come to ~86000 satoshi's = 0.00086 =~ $14 (at current preev rate).

Granted, this is way higher than i'm comfortable with, but if you payed $33, it either means you had a large transaction (many inputs/outputs) OR your wallet screwed up.

Mind telling us which wallet you were using?

you can use locktime for this to, altough nobody is stopping you from doublespending the unspent output that was used as an input for the low fee/locked transaction... So the whole thing would be rather pointless.

the reasons for the current high fee when converted to FIAT are dual:
1) the fact that the current transaction volume is higher than the capacity of the blocks
2) bitcoin does not care about the fiat value... The current fiat value went trough the roof, so when you payed a 0.001 BTC fee in the past, the fiat equivalent was much lower than when you're paying a 0.001 BTC fee right now

I do agree that the fiat price of an average transaction fee is waaaay higher than it *should* be, but like others have already said: the lightning network is being developed, and if more and more people would switch to a segwit wallet, the problem should also become less pronounced.

well, you need to double check that the input (vin) is indeed the unconfirmed unspent output to your change address, then you need to double check that the address being funded by the output (vout) is indeed your address, and that the value is indeed the value of the input minus a rather big fee. You can either trust my wizard and assume that the difference between inputs and outputs is suffienctly large as a fee, or you can manually re-calculate the fee... It's up to you

It's actually quite hard to explain this in detail... This is why i made a wizard a long time ago...
1) surf to http://www.mocacinno.com/page/feechecker
2) enter the transactionid of the stuck transaction
3) near the bottom of the page, you'll see a section called CPFP
4) this section has (in your case) 2 buttons: one creating a CPFP with the unspent output that went to the other party, one creating a CPFP with the unspent output that went to your change address. Obviously, you need to select the button creating a CPFP with the unspent output to your change address (since you don't posses the other party's private keys).
5) double check, tripple check, quadripple check the transaction, i would suggest not to use the decoder on my site alone, but also run the raw transaction trough a thirth party raw transaction decoder like https://blockchain.info/decode-tx
6) if you're happy with the end result, you need to sign the raw transaction... Open the debug console again, and type "signrawtransaction [therawtransaction". The output will be a signed, raw transaction
7) try a different raw transaction decoder, check for the 100th time
if you're happy with the end result, open your debug console and type "sendrawtransaction [rawsignedtransaction]"

I would like to comment on your first sollution: it's not technically correct...
The average time between 2 blocks will be 10 minutes. If more ASIC's get turned on (more hashrate enters the network), the average time between 2 blocks declines, and vice-versa.
Every 2016 blocks, the difficulty gets adjusted, so the average time between 2 blocks is 10 minutes once again, however, there is no guarantee the average time between 2 blocks will still be 10 minutes a couple minutes after the last diff adjustment.

If the time between the block at height a and a+1 is, for example, 20 minutes, there is no guarantee whatsoever that the time between block at height a+1 and a+2 will be less than 10 minutes...

Also, it's possible there are hundreds of Mb of unconfired transactions in the mempool that all have a higher fee than your transaction, so even if the blocks were faster, you'd still need to outbid them... So there is no need to look at a block explorer and broadcast your transaction after you see that the time between two blocks was bigger than 10 minutes, it simply does not matter...

The fee depends on the size of the transaction. The size of the transaction depends on the number of inputs and outputs, not their value.
A miner will usually pick the transaction with the highest fee/byte and put those transactions into the block he's currently trying to solve. The higher your fee, the more miners will have your transaction in the block they're solving, the bigger the chance your transaction will be in the next solved block.

At this moment, 2 things are going on:
- a lot of transactions are being broadcasted. In order to ensure a fast confirmation, people are using higher and higher fees... You either outbid them by using yet a higher fee, or you risk having to wait hours/days or even see the network forget about your transaction
- the FIAT price is exploding... Since BTC doesn't care about fiat, and the fee isn't related to the value of the outputs, this has as a side effect that the fiat equivalent of the fee is also exploding

The high fees are *probably* something temporarry, altough there is no way to be sure that these fees aren't the new *standard*
The community is working on sollutions like the lightning network. I'm not into bitcoin politics, so i won't disclose wether i'm pro or contra, but you can read up on this sollution if you want... do know that it's still in development.

A different "sollution" would be to use a lower fee, and just wait it out... It's possible you'll have to re-create a certain transaction a couple of times before it gets into a block

A last "sollution" would be to switch to an altcoin for smaller payments. For example ETH or LTC have low fees (in FIAT) and fast confirmations (for example, i haven't seen a full Litecoin block in a while... Not that i check that often tough)

bitcoin is decentralised... Unless you live in north korea and don't have admin access to any computer in your country, you can ALWAYS use a desktop wallet... Even then, as long as you have access to the internet, you can use blockchain.info... I would not recommand using an online wallet tough, but if you have no other choice, i'd go for that one...

If you read the link to my website i posted earlyer, you'll see all possible options for speeding up your transaction... Granted, there are only a few of them, and some are technically hard to understand, but that's about it...

Good luck!

In that case, i'd suggest to move to a decent wallet asap... Which wallet were you using?

you created a transaction with a fee of 55 satoshi's per byte
https://bitcoinfees.earn.com/ teaches us the recommanded fee for a 95% chance of getting into the next 3 blocks = 390 satoshi's per byte (at the time of writing).
At this moment, it's ESTIMATED your transaction *might* be included in one of the next 105 blocks (on average, the time between 2 blocks is 10 minutes). However, this is just an estimation... A lot can happen in the meantime

A long time ago, i wrote a wizard to help people that sent a tx with insufficient fees:
http://www.mocacinno.com/feecheck.php?txid=e93d6827e89027a70ed76184590b6dcde7784883fa9ea622ba67376e11d92e97
Granted, it's outdated, some links might no longer work, and with the introduction of segwit wallets, things also changed... But for a non-segwit wallet, the theory still stands.