I didn't read the full post, but I wanted to comment on trustless P2P exchanges. Most payment methods people want to exchange for Bitcoin (PayPal, credit cards, bank transfers, etc) inherently require trust. Until that demand changes, all P2P exchanges seem destined to require trust as a central component.
It will be exciting indeed when cryptocoins are adopted widely enough that a design such as you suggest can be popular.
Sure, but low-friction, trustless P2P exchanges between crypto-currencies would be a very useful step, combined with some other projects.
One place where it would help with the USD<->Bitcoin problem would be in combination with a parallel currency with that had its money supply automatically adjusting to keep it stable against USD. You'd then have low-friction p2p exchanges to trade between between Bitcoin and that. This wouldn't directly solve with the core problem of what to do if you have a bunch of USD and need some Bitcoins, but it would mitigate a lot of the problems you get when the exchanges fail; For example, you'd have a decentralized way to do price discovery, and you'd also be able to hedge easily and cheaply against currency volatility. It would also probably make it easier to sell cryto-currency for USD, because it's easier to run a shop for something that doesn't change in value very often than an exchange for something that does.