For the rust conversion to primer use "one-step". It is a product from a company called rustmort. In autobody shop at school we put it on a rusty fender and put the fender on the roof of the shop. So it went through a years worth of weather, and there is no rust to speak of showing back up. Now it's on it's third year and still no rust. My shop teacher swears by it and reccomends nothing else but that. I used it on my s*ittybuilt rear bumper, and then sprayed rustoleum over it, and it's awesome. Tough too, I've slammed my bumper into trees and it doesn't affect the paint.
