Duck and Cover

As I recall it, if you destroy the Vats first, then kill the Master, the Vats will "respawn", and you will have to destroy it again to beat the game. Nope, the Vats doesn't respawn. On a sidenote, getting the water chip isn't required to complete the game if you blow up the military base ...

Damnit! Now you made me wanna replay it to!

Gauss gun for sniping, and the best energy rifle for close quarters (the one you can find in the BOS bunker in SanFran).

As I recall it, if you destroy the Vats first, then kill the Master, the Vats will "respawn", and you will have to destroy it again to beat the game.