The breaks in your arm probably came from trying to do jumps before you could carve, no offense. You gotta learn to ride before you can start doing tricks, having plenty of boarding experience you'll progress quickly, but for the love of your limbs, wait until you're comfortable on black diamond terrain at least before you start flying off stuff. You might wanna even take a few lessons to break some bad habits, since you're using the heelside turn as crutch, and you're going to be wanting to 'surf' the board.
He's my exact size, what I got was a Rome Solution 158, it's a nice enough board to not hold him back, since I'm sure he'll move along quick, but it's not a beast either so he'll be able to learn on it. If you can find last years, you should be able to pick one up for $250. That's just one suggestion based on what I got, there are dozens of options out there. I'd go with something 156-158.