Which president was a famous Rhodes Scholar at Oxford?

Which president's middle initial "S" famously stood for nothing? What was Ulysses S. Grant's original first name? What was Bill Clinton's birth name? What was Gerald Ford's birth name? 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?