Stick with the same product line for 1, if your using a rattle can they make differant types of paint, use the same type clear as the paint is such as acrilic enamel go with a acrilic enamel clear dont mix them up or you may regret it, oh and one more tip if going to prime then sand use bumper paint/primer as it is made to flex. most all rattle cans are single stage and it already clears to a nice finish I would not try to clear over that, if you are shooting a base coat only then yes clear it.