The client has to validate every single block to ensure that the transactions and the block itself is valid. The validation process includes the client extracting and compiling unspent outputs from the blocks and information relating to the addresses in the wallet. If it doesn't then it wouldn't be trustless and it would have to rely someone else to provide it the correct information. It's basically the only resource intensive part.

If you're using the GUI,

Go to Help>Debug Window> Current number of blocks. You should be able to see the number of blocks processed and the timestamp of the last block that is processed.

If you hover your cursor over the bar, you should be able to see the number of blocks too.

Excluding landspace and electrical fees right?
Given that Bitmain S9i is the most efficient ASIC,
Number of S9is you can get: 2770
Amount of hashrate: 38780
If the hashrate increases at 10% per month, you can get about 50BTC per month.
Depends on your operating cost.
Yes. You just need loads and loads of resources (ie. land, electricity, funds). You have to contact the ASIC company for bulk orders but the shipping fees would be pretty nightmarish.

When the network realises the attack, then it would be too late. 51% attacks are essentially an attacker building their own private chain alongside the honest chain. When the time is ripe, they will release the chain and the history of the other chain would essentially be wiped clean.

Nodes can't reject blocks as they wish, unfortunately. They could invalidate the chain but it would have to be done manually and the client would probably have to be modified. The attack can continue after the release of the chain too, as long as they can sustain 51% of the hashrate.

As long as they have 51% of the hashrate, they can spend every single transaction again after its spent, no matter how many confirmations they have. They can double spend as many transactions, for as long as they want as long as they can sustain it.

They can't violate protocol rules but double spending is very damaging.

Its possible. The data structure for every OS is the same, AFAIK.

Just install the client as how you would usually do. You can either copy the entire data directory to the default data directory or to a different directory. For OS with UI, the client will prompt you to select a data directory if it doesn't detect it in the default directory. You can always point your client to the directory in the conf file or at startup.

More Bitcoins being mined doesn't mean that it would be more susceptible to a 51% attack.

If Bitcoin becomes more expensive, it would be a possibility. They would be able to get a larger profit of fiat if they execute a 51% attack for the same amount of Bitcoins. The main factor affecting the cost of Bitcoin is the network's hashrate. If more people are mining, it is harder for anyone to be able to control 51% of the network as it would require more hashrate and money.

It's centralised as any entity controlling over 50% of the network's hashing power will be able to generate blocks faster than anyone else and hence no one would have a chance to get any blocks against them. This doesn't allow them to violate any protocol rules. Bitcoin functions on trusting the longest valid chain as the main chain and disregarding any other. As a result, they can potentially spend a coin twice by making nodes discarding the chain with the original transaction in and including the chain with their own transaction that spends the same inputs.
No 51% attacks has happened on Bitcoin.
No.
Not exactly. Anyone with a quantum computers can crack public keys within a reasonable timeframe but they are only exposed when UTXOs are being spent. If you just send Bitcoins to an address that has never been used, it is not possible for anyone to steal your coins with a quantum computer.

Electrum has two options; to encrypt the wallet files or private keys only. If you encrypted the wallet file, you will not be able to get into the wallet and view its content without a password. If you encrypted your private keys only, you will be able to see your addresses and transactions but you will have to key in a password to decrypt it if you are doing anything requiring the use of the private key.

What's the problem that you're facing?

Most GPU/ASIC resistant algorithms aren't that resistant actually. Anyways, mining using CPUs on a device that is not designed to handle high loads seems to be pretty bad.
Could you link me to some of the pool resistant coins? I haven't found any on the internet.

If the block time is lowered, I would say that the price would be much lower too. The profits would likely remain somewhat the same but there's a feel good factor about mining a block. Any rational person would judge on their profitability solely on the numbers though.

I doubt any coin could ever be truly botnet resistant. GPU and ASICs? Maybe but having botnet resistance is a stretch.

Other than the mentioned point, nodes only accept transactions/blocks that follows the network rules and thus are essentially enforcers of it. If non-mining nodes doesn't exist, then everyone is assumed to be running a SPV client. SPV clients do not validate blocks and they assume that every transaction in a given block of the longest chain is valid. SPV clients connects to several nodes for this purpose. (Sybil) Attacks against are made more expensive with more nodes as a single honest node would make it extremely expensive. If there were no non-mining nodes at all, miners would have total control of the Blockchain. They can essentially work together and change the protocol rules of Bitcoin and its not what we want.

Um, using 2 billion dollars of USD. If they want to execute an attack, they would have either a participant with sufficiently high hashrate or someone controlling a pool with that much. Once you get the hardware, electricity costs shouldn't be that huge of a concern.

The website assumes that someone has 51% of the hashrate and is willing to lend them out to the attacker at the rate that NiceHash is offering. Plausible, of course. I doubt the total amount that can't profit from mining but still turn their ASICs would collectively have 51% of the network. 1 minute is nowhere near enough to do anything to Bitcoin. You need at least 20 minutes. Reward isn't big either, unless you're telling me that the person isn't requiring at least 3 confirmations.

Difficulty of 1 is the easiest. Lengthwise, and barring any difficulty increase, maybe?
Unfortunately, no. I briefly scoured over the code and I couldn't find the relevant code (was a quick one since I'm on my phone right now). Generally, the blocks in the same target/nBits (difficulty) are considered to have the same amount of proof of work. I believe this would be the only logical explanation and its the only one I know.

Maybe achow101, HCP, Loyce and bob123 can help to point out the relevant codes; pretty curious too.

Difficulty-wise as in the chain with the longest proof of work. The longest chain with the highest accumulated difficulty requires more effort to make than another chain but with a much lower accumulated difficulty.

It doesn't have to be the longest chain but it has to be the one with the highest total proof of work. It wouldn't make sense to consider the chain length since its easy to produce blocks with a difficulty of 1.

You cannot merge any forks. Once the forks has blocks that has different rules or blocks that are different, the entire blockchain after that point in time will be different completely.
Both are valid. If both chains do not contain blocks or transactions that violates the protocol rules, they won't be invalid. The nodes would see two different chains with differing proof of work. The network will see the different chain and only accept the one with the longest proof of work, discarding the others.
Yes. If its longer difficulty-wise, nodes will take that chain and build on it.

Lmao no shit. How is that constructive? Stop trying to pad your post count with nonsense. Address the questions or just suck it up and stop questioning their decision.
Its simple counting. If you're wondering, a 5 year old can probably count better than you. It isn't even in sequence ffs.

Is it offtopic, a necrobump? You have to give us examples for us to tell you why. Certain threads are self moderated and the OP can delete the posts in their thread.
Threads which has been trashcanned doesn't need a message to be sent by the system, IIRC.
It's good that you're putting effort to post. It's not good if you're posting some rubbish (no matter how constructive it is) to a thread that has nothing to do with it or if its from a long time ago and is no longer relevant. I'm not directing it towards you but I'm just saying a post with loads of content =/ constructive.

Any improvement has to be minimal or else it would be the Segwit vs Block size increase fiasco all over again. I doubt Bitcoin can ever be a privacy-centric coin so that is out of the question. On the other hand, Bitcoin could potentially try to be a currency that can be used to transact in the real world. It wouldn't make sense for confirmations to take up to an hour, sometimes even more. Bitcoin has to be able to sustain high transaction volumes and effectively lower the risk for 0-conf transactions. I doubt a block interval decrease would be possible.

Yes.
Bitcoin doesn't have a central authority and that is a feature of Bitcoin. In the real world, fiat can be forced to return with a court order or a lawsuit. This can only be fair if the judges are fair about it and it wouldn't always be the case. Bitcoin can't have anyone to judge if your coins are lost or stolen and rightfully belong to you. It seems logical for everyone to be responsible for their own coins.

Technological advancement would make mining much cheaper in certain countries. By the time 2140 comes, miners would probably have ROI'd on their last ASICs and they are earning pure profit. There is nothing to lose by keeping them on.

I predict that some ASIC farms would drop out from the race and the mining equilibrium would keep mining profitable. Bitcoin could be worth more and scaling could ensure that the fees/block is substantially higher.