Never attempted to paint a car the right way. I immediately hit metal using 80 grit, didn't expect that doing it by hand. If I use an orbital sander am I going to create thin spots in the metal with 80 grit? I do want to take my time and do it right, but I don't have a lot of spare time, nights and weekends. Will the bare metal start rusting in-between days working on it? I also keep staring at the word mustang sunken in on the rear bumper, any tricks to sanding that without ruining the sharp edges of the letters?