1. How do you intend to get around the terms-of-use violations for most of these MMOs that explicitly state that buying in-game currency is forbidden? I honestly have only played WoW from that whole list, so I'm not much of a gamer myself, but I know that Blizzard at least is very aggressive in making these sorts of things difficult, or at least a bannable offense if caught. Especially for selling whole accounts.
As the owner of
https://ferroh.com/d3 , I can tell you that Blizzard does not appear to care whether you buy D3 gold.
The trade forum is filled with people trading gold for paypal, and I have never seen Blizzard delete such a thread.
The situation with WoW is a little different. Real money gold trading might change a bit when Blizzard adds gold to the RMAH (it's still not available there).