PAUL THOMAS MITCHELL, 46, of New York, a firefighter for the New York Fire Department, got the nickname “Big Daddy” because of his six-foot, four-inch height. The nickname worked on other levels, too. “Even chiefs came to him for advice,” said friend and firefighter Christopher Gunn. “Paul had an answer for everything.” He also unfailingly came to the aid of family, friends, neighbors - even strangers - in need. “Never, in all my years of knowing Paul, did I ever hear him say no to anybody,” said friend Gary Barton. “If you needed a hand, somehow Big Daddy was always there.”