The foot surface area is the tips of the toes or the toe box of the shoe. It is not a recommended strike zone for training young players. Unfortunately, too many players forego proper passing technique to gain the extra power a toe poke provides. The toe poke produces a pass that scoots instead of rolls. It is also a fairly inaccurate technique.
Heel can be very useful to provide a surprise passing direction.
Though the heel has as much power potential as the toe poke, it is most often used for short quick passing. Outside of the foot is not a very useful technique. The area of the foot is exactly opposite that of the inside of the foot. Sole of the foot is the least used passing surface. Good dribblers that use the sole of their foot for ball control find this pass useful in certain situations.