no
no you cant steam friends in an acount.
You Can't I'm Sorry :(
Through steam pipes.
no steam retail codes cant be reused
No, once a game is added to an account, it is non-transferable. The only way to transfer the game at that point would be to give the whole account.
You can't.
if you've got the Xbox version you cannot get more weapons. however if you've downloaded it off steam you can pick them up. to download steam make a account and download tf2 its free. hope my answer helps.
Restoring your computer will not affect your items in Team Fortress 2 in any way. All items are stored to your Steam Account through Steam-Cloud.
Yes, but it must be purchased as a gift for someone. You must have their email or steam account. You cannot transfer a copy that belongs to you. Only one that you have bought to gift to someone.
I purchased Portal 2 but accidently assigned the steam account to my sister's PSN account rather then mine. How, if possible, could I re-assign my steam account to my PSN account?
Well if you are on the same account it won't make you buy it again.
No.