Drywall Contractor: Start and Run a Money-Making Business by Anthony Dougherty (McGraw-Hill, 1994; 212/512-2000). Softcover, 73/8x91/8, 262 pages. $18.95. I sometimes judge the value of a book by comparing the table of contents to the number of pages. So when I first picked up Drywall Contractor, I assumed I would find little more than tip-of-the iceberg treatment of its subject. While that is true in some areas, the amount of information compressed into 262 pages is impressive. In addition to offering very good reading, this book could save budding drywall contractors many times its nominal cost by helping them to avoid what they would otherwise learn from the expensive school of hard knocks. A questionnaire in the first chapter forces the reader to take a