Daedalus Books & Music, an 18-year-old mail order company, has moved to new headquarters, a 146,000-square-foot office and warehouse at 9645 Gerwig Lane, Columbia. The company's catalogs, which specialize in remaindered books, new works and compact discs, have a yearly circulation of 5.5 million. The move from the company's Hyattsville offices has quadrupled its space. A retail store is planned.