If you got the Email, Cd-key, Adress, Full name, Account name and Password that account is basicly yours. But as he had the CD-Key he can recall it but I think there's a few guides in the scamming section how to prevent accounts from getting recalled.
What can you do with the account?
Well, either you sell it (If you know he wont recall it) I've sold accounts that's been recalled without anything happedning but I've heard people getting in debth with paypal which just causes extra problems.
You can keep the account and play on it.
There's quite alot of thing you can do with that account actually. I didn't really understand what you ment about the other accounts but if it's the same as this one same goes for it.