[Bigboy4613]

You are a quick study and almost there. You don't have to let epoxy primer dry before additional coats just a good flash time but epoxy primer is a great seal on metal but additional coats won't give you a lot of build. The advantage of epoxy is great seal on metal and you can do body work on top of it. And self etchin and a good 2k urethane primer will provide a really good seal as well acting as a moisture barrier its just not that you would want to put a self etch a 2k primer outside in the elements for for a few years and then sand and paint. Epoxy is the best as a moisture barrier damn tough stuff 2k urethane primer is not reversible meaning it wont absorb moisture but left outside in the elements the pigments and extender pigments will degrade over time and let the elements through.