gingerbread,
Your son is how old again? And you have all this figured out? Why not talk to those who have much more experience? Every position throws basic fastballs yet most arm problems belong to pitchers. The easiest pitch to throw is the fastball. The other positions don't throw anything except straight fastballs.
I would like to hear from you when your son is 20 years old. Very seldom do the problems show up at 9, 10 or even 13 years old. Many outstanding 13 year olds became average 18 year olds. In the interest of your son... I recommend that you seek more advice! Most every parent thinks their son is doing everything right because he appears to be healthy... until the future MRI results prove differently. That is when you really start realizing you didn't actually have everything figured out quite right.
BTW, that video (can't remember whose son it was) was pretty impressive.