Agree.
IMO, anything the cops/feds have in their arsenal should be legal for the citizens. The point of 2A is that the citizens should have the means of protecting themselves against an oppressive government. So if the cops/feds have grenades, they should be legal for the rest of us.
Yep. "Arms" is arms. Not just guns. The principle still applies when it's phasers and photon torpedoes.