WHICH son of a big real estate investor became so aggressively deranged at Dorrian's on Second Avenue, he fought with the bouncer who threw him out, and then kicked in the bar's plate-glass windows? His business partner quickly offered to pay for repairs to prevent cops from arresting him . . . WHICH two Hollywood buddies should go home to their wives instead of partying together in New York clubs with bags of cocaine? . . . WHICH sitcom actor avoids socializing with industry professionals? Though his flamboyance is obvious, he stays in the closet with his close-knit - and tight-lipped - circle of gay friends.