Filler cure - that depends on the amount of catalyst used, the ambient temperature and the humidity. Too much catalyst - a gooey mess that will take days, too little, same thing. You can also use a polyester high fill primer (Everfil) for the little dings and depressions

'79 Ford emblems and trim are all mechanically held in place - no 2 side tape - that is, at least on the one I had.

Primer - 2K will cure in 30 minutes to overnight - again, this can be weather related. Epoxy - overnight, regardless. I suggest that the acrylic lacquer base primers never be used unless you are using acrylic lacquer or an older single stage enamel as it is NOT much of a protectant from weather. If you are going to bare metal - then for sure, epoxy is the best primer.