Importing Maya Character Rig into Unity

Hello everyone! I have a question that I've tried to solve myself with no luck for quite some time.

I'm a beginner at programming, unity, and 3D models so please bear with me.

Attached I have a rigged model of a small knight man that I've slaved over to make and I've run into a few problems.

1) Why is he so jerky and clunky when I load him into Unity? I've seen other models that are literally 40x his size and they can spin around flawlessly, but when I spin the knight around it's incredibly choppy and 'laggy'.

2) I can near guarantee you that he is in the middle of the grid, as I've spent countless attempts to make sure of that, but when I put him into my game I have a simple 'rotate player to where the mouse is' that I learned to do from a tutorial (the 2014 unity tutorial of the boy shooting nightmare bunnies) and as I rotate him he doesn't stay stationary... he has a slight wobble to him that makes me thinks he's not center.

Any suggestions or thoughts would be greatly, greatly appreciated! I'm at a total loss on how to approach either of these topics at this point.
Thanks!
-Drew