spray and pray... chuck it into burst
mode, and shoot away.
bring a laptop if you feel you might need to take a dump during the night.
not good for the shutter nor the workflow but that way you have less excuse for missing the shots u wanted.
last band i shot had really bad lighting - the usual lighting guy offloaded his duties to a bunch of monkeys who just pressed buttons all night. i ended up culling 2/3 of what i shot. but i feel it was worth it.
try rock up a little before the night starts so you can fire off some test shots and get a feel for space- that'll help you choose lens. it'll also give you some time to test out what shutter speeds to aim for, etc. if needed, shift furniture backwards to give yourself some room.
the 70-200 will be excellent for headshots and hands on instruments.
shouldnt generally need to go wider than 18mm imo.. just depends
oh and shutter speeds- 1/100 = very lucky in most lol
1/30 and a lot of culling should get you enough keepers (you could even get a fair few keepers at 1/10)
hope this helps (and makes sense)
time to hit the hay
-julz