Re: removing paint
All you need to do is scuff the paint, you don't need to remove it as long as it is still on the engine good.
If is is peeling then you would want to strip it but just to repaint you don't need to remove the old paint.
I would use 400-600 wet, give it a good scuff, wash it off with regular water, dry and paint it.
If you want a nice paint job take your time, get a tack cloth and wipe it down right before you paint, it is all about prep, the longer you spend getting it ready to paint the nicer it will come out.
The difference between a $400 paint job and a $4000 paint job is about 100 hours, everything else is the same.