For nearly two weeks, Senator John F. Kerry had refrained from commenting directly on the crescendo of attacks on his Vietnam War record.............. At first, some of Kerry's allies thought that a response from the candidate would merely prolong the publicity...... "I personally miscalculated," said Paul Nace, who has worked closely with Kerry in his campaigns since 1970. "There were a number of us who were following it closely and trying to measure it and you don't want to react and give a story more legs than it is entitled to. But when it became clear the story did have...