I would suggest scuffing the rack with a 3m scotchbrite pad, just enough to make it dull. They make several different ones- you want the red ones. I forget the part number but can look if you want. That rack may take some time & effort as I've found sanding some powdercoat finishes to be like sanding a concrete floor.
Wipe it down with a damp rag followed immeditly with a clean dry rag
I would skip the primer and use quality trim black areosol from an autobody supply house. SEM is a brand I've used a lot. Most Napa stores have a body supply section and there stuff is decent.
Good luck and breath deep.
