Getting all bitcoins would end up being super expensive, don't think it is realistic possibility. But if that would happend, we would most likely move on to another cryptocurrency.
There is no blacklisting in place. Problem with it would be who would decide to start blacklisting? Just take your word after you bought the car to blacklist funds "because they were stolen"? I doubt anyone wants to allow US Court / Gov to start blacklisting peoples funds at wish?
Only way if you want to try recover funds is to follow the money-trail as long untill funds hits some known entity to ask from them who gave money for them and start following money-trail. Just expect it to be broken at some point & its easy to mix that money to quite untraceable.
I assume you refer as a official version to bitcoin-qt Haven't really tried but it should be. On previous version you can set transaction fee from wallets settings.
Even tho if you can do it you shouldn't. Miners reserves their fee + sometimes it can take quite long before your transaction is confirmed.
Quick searching gave me btc-e exchange (https://btc-e.com/ ) witch does trade litecoins and namecoins. I have no information from sites collecting this information from different exchanges (including alternative coins also).