First thing's first. Congrats to your hubby's friend's little bro for passing the ATC course. When I was in how many years ago, it had a pretty high wash out rate. Heard it's a pretty stressful job but just like what Rmull27 mentioned, it'll be all worthwhile in the end. ATC's make pretty good money once they get out and transition over to the civilian sector.
Also be glad that he's not stationed at an ACC base where they have combat aircraft. They tend to get very busy w/ all those inflight emergencies. Again, good luck to your hubby's friend's little brother.
Also when you get out you're already qualified, and in the civilian world I believe they are able to retire at 20 years, you can correct me if I'm wrong. If he decides to get out he will always have a fall back option in case something happens. Honestly stay clean and he'll do great.
Hobbies are good, but they are hard to come by especially if they are doing panama schedule. I know when I was in tech school is was all "gun-ho" about being in for 20 years, then I went to my first station and said "F this, I want to go into the real world again".
I recommend study study study if he wants to make his ranks. If he is serious, he needs to get Staff his first time (just makes life easier), but it's all a judgment call.
I don't want to make Staff right now just because of leadership and how much my supervisors get crapped on. I don't want to be stressed like that and have to come in on odd hours because one of my airmen decided to screw up and go to jail.