actually, using BCUT to edit HP values would be best...
as far as what's being asked here:
1)
Weapons should drain no energy from the ship.
go to Edit Torpedo Properties
set Normal Power to 0
go to Edit Weapon Properties
click on the Phaser Proerty (might be called something different)
set Normal Power to 0
i think that should do it...  also you might have to change a value if pulse weapons are used, it would be Normal Power to 0 there...
im not 100% sure on this tho...
2) 
Shields should be invincible (it shouldnt be possible to disable them) 
go to Edit Shield Properties
set Max Condition to a really high value
set each Max Shield (Front, Rear, Top, Bottom, etc) to a really high number like 100000 or even higher
set each Shield Charge to a high number like 100 or even higher
3)
Unlimited torpedoes
 go to Edit Torpedo Properties
for each Torpedo type listed, go to Torpedo Amount and set it to a very high number, perhaps 1000 or 10000 or whatever...  granted, it isnt "unlimited" per se, but you wont run out during any QB match...