I haven't played much in the way of FPS games but I have played Team Fortress 2 a lot, using basically its default keybindings. I saw a number of options including pregen packages but I'm not really too sure what will really suit my usual playstyle well, so do any of you have some good suggestions for keybindings?

Also is it true that the melee hits only count in this game when your animation connects to the target, as opposed to when you click it? Because that would actually be an improvement over TF2 where it counts when you click rather than your animation, which confused me for a while when learning to use melee attacks there.

I haven't played TF2, and so I can't comment on differences between the key bindings of the two games.

I'd say just give Thief 1 a try using the defaults and see how it feels. You can go through the tutorial to test a number of different functions, and the first level starts you in the streets without any immediate threats. Correct, a hit doesn't hurt unless it connects. Be aware that it also doesn't hurt if it gets blocked (ex. your sword hits an enemy's weapon). You'll have to aim your arrows to account for arrow arc (with some exceptions) as well, and travel time isn't instant.