Get get a shorter stem on there, it does affect the geo / handling but for getting the basics and balance it'll be fine.
Bar wise, I'd say just over shoulder width is about right. If he holds his hands out infront of him shoulder width apart with his thumbs in line with his shoulders (his hands are 'over'' shoulder width) I;d go for something like that.
You want as wide as he can get away with, but if his forearms angle out because the bars are too wide thats not good.
Oh, and I don't know what position his bars are in right now but if the rising section is in a vertical position rather than a rolled forward position it'll move his hands closer to his body by a couple cm's