'So, what do you do?' Whenever people asked him, Eric Cash used to have a dozen answers. Artist, actor, screenwriter. But now he's thirty-five years old and he's still living on the Lower East Side, still in the restaurant business, still serving the people he wanted to be. What does Eric do? He manages. Not like Ike Marcus. Ike was young, good-looking, people liked him. Ask him what he did, he wouldn't say tending bar. He was going places-until two street kids stepped up to him and Eric on