1). The work done is the potential energy the football has after it is raised.
Weight of the football = (Mass) x (gravity) = (0.5) x (9.8) = 4.9 newtons
Work= (force) x (distance) = (4.9 newtons) x (0.8 meter) = 3.92 joules
2). Power = (work) / (time) (You know this from the car problem.)
Power = (3.92 joules) / 0.25 s) = 15.68 joules per second = 15.68 watts.