by Claudine Zap The theme has been picked. The invites have gone out. All that's left for prom-goers to decide: Everything. The dress, the hair, maybe even a date. But before potential prom kings and queens hit the dance floor, they've flocked to the Web for Prom 101 assistance. Here, a Buzz roundup of prom trends. Dance, dance revolution While the high school students sure clean up nice for the night, it's the dirty dancing that has school officials in places like Newark,