One of the easiest methods I have used to get the surface adequately prepped is a wire wheel on an angle grinder. Only when it is steel, though. It will go through decals, rust and anything other than the tubing without leaving the sandscratches that most other methods short of chemicals will do, plus the rust is no longer an issue.
As long as your primer is matched to the brand of paint you are using, which is a generally good policy as some are wierd that way, you shouldn't have to wait that long for recoats or sanding. Most primers can be sanded within 1-2 hours and color coated within as long.
Sand the primer with 400 and 600 grit sandpaper by hand until smooth and coat with your color set of choice. If you choose a clearcoat to match the color, be sure to keep within the recoat window, as it is important for adhesion. If you wait too long to recoat, the bonding of the layers is reduced and can make lifts or peeling.
For added shine, after a sufficient time of hardening(such as a couple weeks if not baked or otherwise heated) wet sand(water in a bucket with soap added) lightly with 1500 grit sandpaper and buff with a very fine rubbing compound. Be careful though, as this can easily go through the layers if not careful, so it may be best left off unless you feel confident about it. Nonetheless, the rubbing compound is safe to do.