Faced with burgeoning rent and an ominous "demolition clause," co-owner (and former hoofer) Rozanne Seelen moved the Drama Book Shop from its longtime 48th Street space to one nearly three times as large (at 250 West 40th) in 2001.The store now has amply stocked shelves, comfortable chairs, and a theatrical touch on the balconyathe outrA(c) red couch by which Nicole Kidman cavorts in Moulin Rouge. The staff has the requisite recondite knowledge, handling with aplomb a customer's inquiry about Hroswith. Who? "An Alsatian nun around the time of Charlemagne," says Seelen, who knows from Alsatian nuns. "She did bowdlerized versions of Plautus."