Buffing?

I don't remember if I saw your car, if it's base/clear you're good to go as long as you have enough coats of clear, at least 3. If it's single stage it has to be non-metallic to sand.

Depends on how much orange peel you have, 2000 is very fine. I start with 1500 or even 1000 if there's a lot. You work through them, 1000, 1500, 2000 and finer if you want. You need a good buffing system as well, I use Norton Liquid Ice which is a single compound system.

You have to be very careful, especially if you've never done it, tape your edges and hard lines or you'll sand or buff through in a heartbeat.