Mallot's Dad,
An invitation to get to know him & his transcipt better is a great start. Absolutely follow up with the requested information and have your son follow up with a phone call to the coach.
It doesn't matter how many notes they sent out. All you should care about is that your son received one. I would expect they will continue their recruiting efforts, and your son will continue his recruiting efforts. If there is a fit for both of you, you will know it and then you take the next step.
Good luck!