I am going though pretty much the same thing. I am still doing metal work so I have some time to figure out what brand of primer and paint I am going with. So far Lesonal has been suggested to me. Not sure if that is what I will do, but am curious to the replies to this post.
I did however invest in Kevin Tetz's Paintucation videos. He has four different videos covering metal repair to actual painting. I, personally found them interesting and helpful. I noticed you can find them on eBay once in a while, but you can find them for sale on various sites on the internet.