Hello, nice to meet you. From where you live you are not alone. We have a number of people close to you that are wonderful with reptiles. I have a friend in Manhattan Beach, but if I think I am sure there are several others.
Your son's cham looks really good for coming off craigs list. You scored on that one. The white spot is fine. If you look you will see a couple more near his head, he is going to shed.
Just from looking I don't see much you are doing wrong.

If he has had a veiled, panther are very much the same in care. He will need a UVB light and water. From where you live the humidity and temp should pretty much take care of t's self. It shows I live in Montana and I do, but I am from CA, and lived in Mission Viejo for 30 years before moving here 5 years ago. So i can help with a lot of your questions.
For now relax and enjoy him and we can fine tune stuff later. Oh if he can have some outside time for some sun, that will be great. I would keep him in a cage and tell your son to stay with his cham.
Welcome again,we are all here to help.