Unfortunately I do not play soccer, however when I was talking to the coach for my sport I did ask about what I should focus on. For college recruiting, exposure is most important. Where is he going to be seen by the most college coaches? Where is competition the best? For my school and sport it was more important that I focus on the club aspect instead of ODP or Varsity as much. Also, club teams generally have better connections to college coaches in my sport, not sure if the same is true for soccer.
About not hearing back: Since it's still pretty early in the game for your son it isn't overly surprising that he hasn't heard back. Don't let that discourage him or you. My mom told me that the squeaky wheel gets the grease. At the same time it's important to not inundate the coach with emails, your son is, after all, a freshman and that puts limits on what the coach can do/talk about. Also, you have to understand he/she is most likely preoccupied with both their current team and their current recruiting class. A potential recruit a few years down the line is probably not at the forefront of his mind. The best move, as I see it, is that your son introduce himself and send periodic updates on his play over the next few years.
Also, when the time comes to talk to his ALO for his application, I'm pretty sure he/she can tag him as a potential recruit for the coach to see.
As a side note, part of college recruiting is talking to multiple schools. Just because a school isn't your number one pick doesn't mean you shouldn't talk to the coach. Coaches talk and perhaps your son's name will come up and trigger further research by the Air Force coach.
Good luck to you and your son. If I survive USAFA and he gets in I may very well be his cadre!
(Please forgive any continuity errors, it's late here and I've been editing lines here and there)