It should be noted that, although this may well be a single stage paint, it is most definitely NOT the same as the old single stage lacquers used back in the '70s and earlier. The chemistry is such that this paint is still a catalyzed coating using technology much closer to a modern clear coat than to what was applied at the factory on a '57 Chevy. Whether the paint is hard, soft, delicate, or otherwise isn't really going to be dictated by the simple fact that you're working on the actual color. Just as clear coats vary all over the place with regard to hardness, so could this single stage vary from one model year to another.
The basic concepts for working on it are identical to those used on a new car with clear coat, except of course that you're pads are all going to change color!