danocaster, Welcome to HSBBW. This is a great site with a lot of good information and helpful members. Here are some helpful tips, as a father of a pitcher who has gone through the process from T-ball to college:
*He's 9 years old. At this age, the most important thing is to have fun, and don't take it too seriously. Let him learn a love for the game naturally.
*I know this sounds crazy, but don't worry too much about mechanics at this point. The reason being is proper mechanics is highly technical--too technical for a 9 y.o. IMHO. If you focus on mechanics he'll probably just learn it wrong and it will be a mess later. If you must, keep it simple. Focus on two things and two things only: 1) When his plant foot lands, can you draw a straight line from his glove hand to his body to the ball (when you are standing behind him)? This is called "staying closed". 2) Keeping the head still and throwing the ball to the mitt. "Smell the mitt".
*Forget about throwing hard. At 9 y.o., this is impossible and probably counter-productive. At about age 12-13 you can start learning ways to increase velocity by regular long-tossing. But not until then.
*Don't let him "pitch" too much at the younger ages. Pitching regularly begins about age 13. If you let him pitch too much at the younger ages the pitching motion and mechanics become engrained and harder to fix when it's important (age 13+).
*Don't mess with his natural arm slot. 3/4 is good, and IMHO the best for combining velocity and movement.
Finally, the landing foot toe actually should point slightly inward. But just slightly. One last point: A kid with a 3/4 arm slot has a tendency to fall just a bit to the left (if RHP) or right (if LHP). This is normal so no worries.