rofl! Sounds alot like me when i was young.
As for Parkour, If i were you, the first step is to increase his upper body workout, especially the forearms, wrists, and hands. A pullup bar is ideal for this. I use one all the time, but not in the traditional sense. First, grab the bar and flip upside down, passing your legs between your arms. Go as far over as you can... and then return to the original resting position. I also have some handles i cut from 1" nylon strap. They have a piece of pvc on them for a handle. I use them to do alot of different workouts specific to forearms and hands. Alot of hanging upside down, flipping around, messing with my center of gravity, and natural pivot pints.
There are several good youtube posters for parkour and free running. A couple of them have videos for sale, which would be another good source. Best advice i could give you already know....... SUPPORT HIM! Help him find cool things to trick off of. tape him from cool angles.He will progress naturally.
A really good way for him to learn to do free standing handstands, and gain incredible upper strength is the following really fun trick...
Elbows tucked into the outside edge of your frame, hands shuolder width apart. Use something very sturdy until you really get the hang of it. Put your hands on the sturdy object and slowly transfer your weight to your hands. As you transfer the weight, pick up your feet and keep your legs straight so they kick out behind you. The idea, at first, is to have your entire body horizontal with all of your weight on your hands.
After you get good at it, you quit using a sturdy surface, and switch to the back of a metal folding chair with nobody sitting in it. The chair adds an element of difficulty because if your balance is not right, the chair will fall backwards under your weight, and your face will land right around the edge of the seat rearranging your dental work. (I have mastered this step and am gradually starting the next step)
The next, and last step..... Go Horizontal on the back of a folding chair, and rotate your legs toward the sky until doing a handstand on the back of the chair.