no steam retail codes cant be reused
no you cant steam friends in an acount.
no
You Can't I'm Sorry :(
You create a steam account and download the steam app
yes
No, it is not possible to play Dota 2 without Steam. Dota 2 is exclusively available on the Steam platform, which serves as its distribution and matchmaking system. To play the game, you must have a Steam account and download the client.
No, you cannot play Day of Defeat: Source without Steam. The game is tied to the Steam platform, which is required for installation, updates, and online multiplayer. Players need a valid Steam account to access and play the game.
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?
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.
No, unless you let them on your account, which is a bad idea and not recommended.
Through steam pipes.