My .02 cents: it is hard to focus on so many tips. But he is squatting and/or on his back foot all the time and using his back foot to turn in. We generally don’t let kids in the course until they can stand up on the ski in the right position for the gates, i.e., hips up, chest up, tall, weight on front foot and balanced. Until a skier can at least stand in the right position behind the boats and for the gate glide it is hard to worry about anything else. Balance, balance, balance, balance, before anything else. Once the kids get this the rest comes a lot easier.