Have you ever wondered what became of a favorite teacher? Theater folks in Cranford specifically, and Union County and Middlesex County generally, might wonder about David Christopher, the former owner of The Acting Studio on North Avenue in Cranford that he originated and ran from 1977-1997. His latest project happened last month with the presentation of the play Hell’s Kitchen NYC, which he co-wrote with Gary Cohen, his former high-school student, friend, and a familiar name in the theater world also as an actor and director. Their hourlong play was accepted by the New York Theater Festival and was presented for three performances at the Hudson Guild Theatre in NYC in late July.