UnScramble this Word: a r e f f c h?

Questions

How many predidents have been assassinated while in office?

Which president had the nickname 'Old Hickory'?

After being shot in 1912, which former president said "It takes more than that to kill a bull moose"?

Who is the only president to be buried in Washington DC?

From who's inaugural speech do these words come, "There is nothing wrong with America, that cannot be cured by what is right with America"?