Not a terribly helpful answer. I'm not sure I 100% understand it, but I'll give you what I think I know.

Pools assign work units, similar to the current block being worked on, however at difficulty 1 (or higher depending on your hashing power), which are called shares. The idea is that you solve your mini-block, and submit it back to the pool, to show your proof of work, out of every X shares submitted, one will also solve the "real" block being worked on (by chance).

So you are in essence solving an easier problem, that can potentially solve a more difficult one, and everyone doing this over and over and over eventually do find a block.

Rich people look for opportunities to make money not spend money.

So if I bought up all the coins it would cost me many millions of dollars. Once only I have them they are worth nothing. Why would I do that?

Do you know that you can divide Bitcoins? Even if someone would by 99.99% Bitcoins the whole global trade could be done with that 00.01%. Althought the whole scenario is as plausible as asking what if somebody buys all the food from the world or something like that...

How about just starting a new coin? Or jumping ship to, say, bytecoin.

Yeah, all it would do is drive the price incredibly high. It's true that if the price gets high enough pretty much everyone would sell. I can't imagine not selling them at $1million a coin...

But as long as there's even 1 Bitcoin left, the whole thing could still run. Remember, the basic unit is actually the Satoshi, which is 0.00000001 of a Bitcoin. So each bitcoin is 100-million Satoshis. If each Bitcoin is worth $1billion, then each Satoshi would be worth $10. Still manageable to run the entire economy off of 1 Bitcoin, but it becomes a hassle at that point as it would need to get divided further down. I'm sure the protocol could be adjusted to further divide it down though.

The biggest problem with that scenario is that whoever is doing the attacking is obviously anti-Bitcoin. Yet what they just did is commit a massive transfer of wealth from anti-Bitcoin individuals, to a bunch of pro-Bitcoin individuals, who now have the knowledge and the incredible wealth behind them to create Bitcoin2.0 (if each 1BTC is a Billion dollars, then literally anyone who's pro-Bitcoin is now a Billionaire). And since Bitcoin is open-source, making a Bitcoin2.0 would be trivial, and this time a hell of a lot more powerful with a bunch of Billionaires backing it.

They would have to keep going until everyone who's anti-fiat is a Billionaire. Personally, I sure hope they do that

you figured it out 99bitcoins

everyone pack up it's over

Not everyone is selling their bitcoins

You seem to think solo-mining is different than pool mining.  They really aren't.  In solo-mining you are communicating directly to your bitcoind but you still request work and return found blocks.  In pool mining you are making the same communications but with a pool server and you also return "shares" (low difficulty hashes) which acts as proof of work in addition to any found blocks.

Well that is a "simple" hashing procedure, no current mining software works that way.  Part of the blockheader include the timestamp.  The timestamp doesn't need to be exact so there is no reason to not run the entire nonce range and return any found shares.

With X-Roll-NTime the local miner software can increment the timestamp for a period of time further reducing the number of getworks needed.  In theory if X-Roll-NTime was set to say 300 sec, the local miner could continually update the block header until it gets a longpoll (notification of change in blockheader -usually because new block is found).  IIRC most pools use a more conservative n-time-rolling value of say 10-30 sec.