Question.

Yes, here. Only in the forums. Otherwise it is against the rules.

You may only submit unused, giftable URLs as giveaways. Individual keys aren't allowed.

You cannot create a giveaway in this site. You can give them away in the forums. If you don't want them to be snatched by some ninjas who will probably not even thank you then you can make it a puzzle that leads to eg pastebin or some other site where you have uploaded the keys.