yes deffentaly a good compressor. our 80gallon eaton cycles quite a bit when spraying a car.
your bare spots you want to feather the edge so you dont feel a lip where the paint is around it with 150. then prime. and block with 600 wet.
as for spray guns. hvlp. ive used a harbor freight and it was not bad. but i usualy use devilbiss GTI. with a 1.4 tip for base, and another gti with a 1.3 tip for clear
primer gun is nice to have seperate. you will want a 1.8-2.0 tip on that.
lay your primer heavy so it fills your scratch.
the euro primer and clear (orange can) seems to work well,
go to any of your auto paint stores. dont be cheep on your paint or no matter how good your gun is it will spray like crap! (duplicolor from advanced!!!!!)
metalux is not bad for the price. along with ppg shopline. both cheeper and have good coverage.
most of the ppg omni that i have sprayed was crappy so stay away from that.