I originally had my car media blasted and primed with urethane. I then did the trail fits (too many to count) and primed with each piece with Nason Select prime (421-20) Primer-surfacer before installing. During the final assemble and wet sand I chipped edges and sanded back down to bare metal. Now that the front is as good as I can get the gaps I am ready for the final priming and block sanding. I can do the painting in a booth at vocational school I attend 1 night a week but I need to do something with the chips/bare metal until then. The first question is for those bare spots, is it OK to cover them with Rust-oleum auto primer (spray can) then spray the entire car with a good 2K urethane for more blocking?? Will these spray can areas cause me problems down the road?
And what would you guys suggest for the final priming product to be able to get good heavy coats on so I can block it without getting down to the bare metal again. BTW, I did cut in most areas (door jams, under hood edges) with B/C but will need to touch up many of those spots as well. Any guidance would be appreciated.

Been there done that/ lol. You can use a spray can to keep things from rusting, but you have to sand it off, before useing a 2k primer or sealer,if not it might lift and blister. As for what to use a a last primer or sealer, you can use just about any type of 2k primer or sealer. I always use top shelf stuff so not to have any problems down the road. I have always tinted my sealer or last primer with some base color. Which kills many birds with one tinting. You will use less base to cover, if you get a rock chip it's not noticeable. Thickness of your last primer is really up to you, you can over or under reduce to acheive mill thinkness or you can add or subtract coats to get your coverage, Remember it's only undercoat not top coat you still have to sand it so don't sweat it, save that for your clear coat.