Thief - the deadly shadows questions

Got this game for christmas. I'm liking, but have a few gameplay questions.

1) Once you notch an arrow and press the mouse button, is there a way you can change your mind put the weapon away without fireing?

2) Is there a way you can make the game autosave at the beginning of a mission? It looks like I have to go through my previous mission again from my last save to get to my current one after I accidently loaded an old game.

3) At times the framerates seem slow - is that just me?

It's been a while since I played it so I don't remember for the first two; as for the third one, I suggest checking out this tweak guide to increase your fps, among other things.