As someone who introduced a couple of kids to modeling, please don't sweat to many of the details. That particular kit will be bit of challenge for an adult, let alone a kid.
This is great time to introduce a few simple concepts like drybushing, but don't sweat it. It's mostly about getting a young man who will naturally be impatient to slow down and then reinforcing it by showing him the successful fruits of his labor.
Just note, that after a few hours of intense concentration, he will also want to go to sleep!
Enjoy the build time together! It's always a blast to see the world through their eyes.
Good Luck! A few of us are probably a bit envious.