Know your Presidents?

Almost political questions we should all know about American Presidents...

Who was the Shortest President of the USA?
Who was the first President born in the United States?
Who married their School Teacher? (Naughty!)
Who married their (basically) adopted daughter in the White House?
Who's Mother and Wife Died on the SAME DAY?
Which one of these do we know for fact had a Secret Baby with his Mistress? DNA evidence successfully proved this in 2005.