Originally Posted by
Binki
1: yes. I have several WoW accounts under my battle.net account, one of them has MoP, one has Cataclysm and one something older (WoTLK or TBC, I don't remember exactly).
2: yes. When logging in you'll see new option to select WoW account that you want to play. As long as you select different WoW accounts, you can play on same battle.net account on several computers at the same time.
3: yes. Its battle.net bound, not WoW account bound.
I'm not sure if you'll be able to transfer character though from MoP account to vanilla. There might be some restrictions.