A Broadway star actor-singer-dancer who has made some inroads in TV, Ben Vereen also has seen his career plagued by personal problems, including a near-fatal car accident in 1992. His elastic movements, ready broad smile, and exuberant energy have made him popular with audiences. But Vereen has also shown himself to be viable dramatic actor with such roles as Chicken George, the mulatto ancestor of Alex Haley, in "Roots" (ABC, 1977). A graduate of NYC's High School of Performing Arts, the multi-talented performer made his Off-Broadway debut not long after completing his studies in "The