With mine, I sent out all the panels & had them dipped/paint stripped. This was a massive time saver & cheap as chips! I then coated all the bare metal in an excellent 2 pack Epoxy which is highly resistant to corrosion (Dupont Nason Ful-Poxy). Once coated, you've got plenty of time to do the repairs. I believe that etch primer won't last long if left uncoated. All the filler work will be done over the epoxy & then resealed with another coat.
I got this advice from a professional painter that's helping me with my car. He really knows his stuff!
Evan.