Denise,
On the first, Keep it simple just as HDNitehawk said.
Second, Set your flash on camera with omni-bounce. Set camera to 'M' with f3.2 to f4, shutter at 200. Not sure how intense it may be. Depending on the ceiling hight I shoot ISO 400, f4.5, 200. This washes out most other lights. On the dance floor if the colored lights hit someones hair you may see that color show up some.
Great info Mark.
Steve U Wine, Food and Photography Student and Connoisseur