Battle.net Account Info : World of Warcraft General Discussions

Hi, I have a few basic questions about how accounts work w/ World of warcraft and battle.net...

1.) If I buy a character through an auction, doesn't the person still have the ability to get the account back with his cd-key?
1b) Would battle.net allow me to enter a fresh CD-key on this account? Will that make the previous cd-key entered useless for Account Info Changes?
1c) Would entering a credit card prevent the person from changing phone/email at a later time? (if he did not know the credit card).
1d) Does character transfer allow you to send a character to a different battle.net account?
1e) Is it possible at this time to approach battle.net with a fresh CD-key, (saying you lost your own), and to have battle.net give you a new Special Question?

Thanks for your help.