[TimT]

I think you have some things out of order on your list


degrease/clean should be #1, this way your not sanding oils/greases/silicones into the existing substrate

also 80 grit is way to rough unless your going to bare metal.

The zinc would be good if going to bare metal, otherwise seal the car using a 2K epoxy sealer

the last car I painted I followed these steps

1: clean/degrease
2: sand (320-400)
3: Seal (epoxy sealer)
4: bodywork/surfacer
5: prime
6: block primer
7: cc/bc
8: cut and buff

depending on how intense you want the blue will dictate which color primer to use.

light= less intense
dark= more