Can a blocked extra point attempt be advanced by the defense?

Answer 1

Yes. A missed field goal that hits the ground results in no points and the opposing team taking possession at the spot of the kick (not the original line of scrimmage). If the opposing team catches the ball and returns it, the recovering team would instead get the ball at the point where the return ends. It is possible to return the missed FG for a touchdown.

Answer 2

In College Football, a blocked extra point can be returned for 2 points for the defending team.

In pro football, however, any change of position instantly kills the play in a PAT situation.

Answer 3

No