Which president was the youngest ever to take office, at age 42?

Who was the first president to be impeached? Which president was impeached twice? Which president served the shortest time in office? Which president was the youngest ever elected? Which president lived to age 100, the longest-lived in U.S. history? Which president was the first to live in the White House? During which president's term did the British burn the White House in 1814? Which two presidents died on the same day, July 4, 1826?