My first suggestion is to read the Terms of Service which is in your World of Warcraft folder or only at the World of Warcraft website where you sign up.

My second suggestion is not use the 2nd account if you want to transfer a character and the name on the 2nd account doesn't have the same last name as on your first account. If the reason you want to use a 2nd account is to transfer characters between them, purchase another copy of the game from a store and create the 2nd account with the same name as on the 1st account.

As for sharing accounts, yes this is against the rules and if caught, the account being shared will be banned. Sharing of accounts doesn't have anything whatsoever to do with names on the accounts. They are completely different subjects. If your friend is not going to play any more at all, you're not sharing it right?