A potentially used key check question

To answer your first question - no, it will just say "Product Already Owned" (just checked it with a used key I bought for my wife yesterday).

I can't answer the 2nd question, sorry.

EDIT: I'd love a way to check to see if a key is used as well, as I have several that I am not sure whether I gave them to friends and they were used, or if they're still available. :/

Sadly no. All you can do is try to activate it on an account that doesn't own it, which would be more than a check as it would be redeemed.

Guess I'll just drop some keys somewhere and hope nobody's too disappointed.

Thanks for the answers.