wow I wish anyone would have wanted to teach me that young.
If you or your knitting friends, have needles let him learn with you and your friends, change needle size, he will find the size he likes.
No. 4 yarn will also let him see the sts as he is doing them. yes I like circlurs too. it might keep him from getting upset and not lose sts. but dropping sts, is learning, to pick them up. You go tiger. learn, ask questions, there are tricks to knitting.