There used to be a sports pack with FiOS. Outside of the NY/NNJ area they've done away with it. Outside those areas the channels that used to be part of the sports pack (e.g. those in the low 300's) have been rolled into the HD Extreme package. So, if you have the Extreme pack you now have all the channels that used to be part of the sports pack.
In the NY/NNJ area, Verizon created a different pricing structure, so they can grab more subscribers in the NYC area. But, because they get better pricing on stuff, Verizon maintained the sports package for those areas. So, if you're in NNJ and you want Blackbelt TV, e.g., you need to get the sports pack. Outside those areas, if you sign up for the Extreme HD package, you get all those channels anyway.
As for your question of getting RSNs from around the country - no Verizon doesn't offer that. Most cable companies don't (I don't know of a provider outside DirecTV, and maybe Dish - although I'm not familiar with their channel packages - that does).