Wet sanding is your best friend for over spray. After each coat let it dry and then wet sand it. We did ours in a small tin shed in the middle of summer, just dont sweat on the paint, lol. I cant remember what we started with. I think it was like 500 grit and then worked up to 2000. We did around about 5 or so coats and it came up awsome.
We used acrylic paint, so just used acrylic thinners to clean as well. Asked a few automotive spraypainters before we started spraying and they said make sure that the bodywork is perfect. This will determine your paint jobs final result.
PS: Neither of us are spraypainters or pannelbeaters so excuse our approach.