TRENTON, May 6 In a debate that was more a get-acquainted session than a heated clash over the issues, the three Republican candidates for United States Senate last night engaged in a largely genial exchange on taxes, Social Security, the environment and combating terrorism. The candidates, all of whom have name recognition in the single-digits, according to recent polls, went to great lengths in a televised debate on New Jersey Network public television to lavish praise on President Bush. They all made passing reference to the ethical questions that have dogged the incumbent they hope to unseat, Democratic Senator Robert...