Do freebies ever get re-added to the giveaway list?

Yes they will be added again i think. but it take some months/years.

i think that bundle games will never be removed from the bundle list, otherwise The Walking Dead would not be there by now :P

At least one Freebie which was removed fro the list eventually got added back as a bundle game (Metro 2033). I think that took a year and a half or so.

The whole point of removing them is to prevent people like you getting CV from freebie keys. They sometimes bring a game back when it's been long enough for most people to have given away their free keys. So it's possible that after a year or two the game might be available again.

You said you have some extra free keys that you don't want? Just give them away in the forum then.