Which president was a sportscaster for the Chicago Cubs on radio before acting?

Which president was a nuclear engineer officer in the U.S. Navy? Which president commanded PT-109 during World War II? Which president was a Navy pilot shot down over the Pacific in World War II? Which president was a college football player at the University of Michigan and turned down NFL offers? Which president was a haberdasher (men's clothing seller) in Kansas City? Which president was a mining engineer before entering politics? Which president was a newspaper publisher in Marion, Ohio? Which president was a professor and president of Princeton University?