I don't have any experience with that particular round head nailer, but I would not try using clipped head nails in a round head nailer. The full head nails are spaced so that the driver can drive one nail. A full head driver would try and drive two nails. Clipped head nails are collated with one nail tight against the next. Also, clipped head nails are collated at a sharper angle and probably would not fit into the magazine on a full head nailer. Trying to use clipped head nails in a full head nailer is a recipe for a disaster.
Very unlikely. Clipped heads are sandwiched and have more nails per inch. Often times the stick of nails is at a different angle as well so they would never fit in the nail slide. Find someone with a suitable gun and give them away.