She used to sing in a + new-wave rock band and now studies art history at Columbia University. But starting this week, she will be spending her evenings curled up on a sofa in a Manhattan TV studio, making wisecracks about the single life in New York City. Typical bit: Rachel charts the differences between a guy she dated named David Sims and former President Franklin D. Roosevelt. "Has fancy cigarette holder. F.D.R.: yes. Sims: no. Tried to pack the...