I need to make about 60 gold & silver stars for cupcake toppers and I have two questions: would it be better to cut them
out of just plain fondant or would a half rf & gp mix be better? Second, what would be the best way to color them? Would an airbrush work?

I would use 50/50 mix. Make your mix in grey and gold, then if you want a shine, spray them with silver and gold luster dust mixed with alcohol, or paint them with luster dust mix . If you start out in color, it doesn't take as much luster dusting.

Are you standing them up? If so, definitely use the mix. I would start out with golden yellow and lt gray, cut the start and then dry dust them. I can't give you any info on the airbrush as I don't have one unfortunately. I like dry dusting things like these as I find they don't get streaky and you don't have to wait for the alcohol to evaporate. Dust one side, flip and do the other, place on cupcake...

Good luck.