Nightclub photography?

I've been asked to take some pics for a club (just a trial for now but hopefully I'll become a regular) but I've never done so before. I study photography so its all very commercially, studio stuff that I've done so far.

I've only got a Nikon D80 just now but it does the job. I have 2 old school Vivitar 283 flashes (with a dial on front ie full, half, 1/8 etc so I understand that. Its just the dial on the side that I don't understand? )

Anyways- what settings should I start with? I know obv I will have to adapt them. But the place will be packed, dark and some coloured strobes. ISO, aperature, exposure?

Any advice would be GREATLY appreciated.

I also have an 18-135mm lens (which I will most likely use) and a 55mm fixed 1.8 lens.

I'm thinking flash going off in a dark club will be distracting. Most club photographers use very fast lenses and whatever light is available. I would be very careful using the 283 with the D80 as if you don't use the correct adaptor you can fry the D80. If you can get hold of an SB 600 that would be ideal. The flash will set the camera correctly and it is very fast so not as distracting as the 283.