Your compressor will be ok and use the HVLP. You can put a cheap disposable water trap at the gun to be safe if you use the 80 gallon. Just make sure the 20 gallon stays up with your pace that way you dont drop in pressure and screw up. I would just screw around on a panel or hood of somekind that you will not use and see if you like the turnout and if so then do your car. Some dirt can be wet sanded and buffed. Just PRE CLEAN the heck out of your car and don't touch it with bare hands! I think you will be fine, don't get all paranoid (sp) over it, take your time and prep it good.