gifts from steamgamesales.com (GamersGate, greenmangaming)

Only if they are steam-redeemable

As far as I know, yes?

Only if they're Steam redeemable (they'll say on the store page). Those are just sales for games, not necessarily Steam games.

If you get a Steam redeemable key from whatever site you buy, you can make a giveaway with it.

thanks, where they say is steam redeemable? or i have to check steamstore for the game and conluzion is steam-reedemable?

Yes you can :). Is this as you buy on steamstore

YES YES YES YES !