I believe the quarterback should stand 4-5 yards.
as far as you want
Your foot can not be placed behind the box. The umpire makes that judgement.If you watch carefully, the first couple batters in a game invariably rub their feet on the ground so as to erase the back...
Yes.
7 feet 9.25 inches from the front of the board to the toe line (known as the Oche)
Seven Foot, Nine and A Quarter Inches - 7' 9.25''