If you plan on doing this for awhile let me recommend the Iwata LHP 100. I have 2 of them, 1 with a 1.4 tip which is dedicated to clear coat and one with a 1.2 tip for base coats erc; I wouldn't use it for a primer gun. These guns are LVLP (low volume and low pressure) meaning they require less air pressure and and use less material than HVLP and conventional guns. If these are too pricey for you I would recommend the ASTRO gun which produces a very good LVLP knock off for less than a hundred bucks last time I looked. They are available form Tool Paradise and other places.
Astro Pneumatic Tool Company EVO4014 - Low Volume Low Pressure (LVLP) Spray Gun - 1.4mm
ToolParadise Database
As far as compressors go, you want to look at CFM and SCFM ratings. If you can afford one I would get at least a 15CFM compressor, this will run most air tools. your LVLP guns require about 7 to 8 CFM i believe. Again you cant have too many, only not enough,. The last thing you need is to have to stop and wait on a compressor in the middle of a clear coating job. AL