I'll take 2 and 3 since I don't have them on GoG yet.
I got into Thief back in the day when Thief 3 came out; a webcomic artist I liked was a Thief fan and wrote up a review about it. He was kinda meh about it overall but what he described sounded cool to me. Not one to just jump in, but this was back in the old days when you couldn't find copies of the game, I'm not ashamed to admit I torrented Thief Gold. I actually found TTLG because I was trying to figure out how to get it to stop freezing.