You should be fine as a firearm is "A firearm is a portable gun, being a barreled weapon that launches one or more projectiles often defined by the action of an explosive". So a grenade is not a firearm
I think not, some retailers think yes. As a rule, I always apply this test if something is dubious: could you rob a shop with it? If the answer is yes or maybe, then count it as an RIF.
