At this time, its likely that both branches will continue to be supported... RMFRP is the latest edition, while RMC is revised/expanded/reprinted RM2, or "fan service" depending on your point of view. As for Pulp and Black Ops, they are for RMSS/FRP. They probably could be converted manually to RMC if you really want, but I would not necessarily recommend that to a new GM. Juggling different editions of rules is not necessarily a good thing unless you have a lot of experience.