The steam cloud and steam achievements are only available on the steam version of the game. The ones that show up for me are just GFWL achievements.
If you liked AA you'll like AC. It's just more Batman fun
. I can't speak for your systems only my own. On my system, DX11 is unplayable even if I turn off AA. I have a higher tolerance to low FPS than most on this forum, it usually won't bother me as long as it can keep an average 24fps, but this one goes way below that threshold so I have to play in DX9.
So torn on what to play later. I want to play Batman, but Skyrim beckons