How a New York Times editor set out to answer the peculiarly marvelous questions of his precocious young son-and wound up on an unexpected journey of his own. Wendell Jamieson's son, Dean, has always had a penchant for . . . odd questions. "Dad," he asked, apropos of nothing, "what would hurt more-getting run over by a car, or getting stung by a jellyfish?" "Dad, why do policemen like donuts…