You don't need 16GB of RAM. You need 16GB of HDD space if you're going to store the blockchain for an online wallet. You don't need that for offline wallet though, you can run the offline version on just about anything made in the last 10 years.
coinbase. You can purchase using USD on btce too but you have to jump through a lot of hoops. I don't think cryptsy even deals in anything other than crypto though. CampBX is good for buying but I wouldn't sell on there.
How is coinbase incredibly expensive, especially when compared to virwox? Coinbase is having a no fees thing tomorrow too but it's a little late to get on that unless you use a credit card which is supposed to be instant.
Either way he's in Europe, I hear bitstamp is pretty good although I've never used them since I'm in the US.
Coinbase and CampBX are probably the best to withdraw USD since they're US based. You'll have through jump through A LOT of hoops+fees to withdraw on foreign exchanges. Coinbase is 1%+a few cents iirc.
I think Sean's Outpost runs entirely on donations so it's not impossible to run entirely from donations. CGminer lets you set up so 90% of your power goes to one pool and 10% to another, it would probably be easier to get people to do that because of the hardware+power costs associated with mining. I'd definitely do it with an altcoin too since you can actually get decent hashrates on scrypt but without an ASIC you'll do next to nothing on btc.