Like I've said three times here already. (Nothing wrong with the reasons you missed training and it good you are taking school seriously) but you just need to let the guy know beforehand so he doesn't think you've flaked out.
I wouldn't call college or uni school. In the UK we finish school at 16, then we go to college or work. If you go to college you can then go on to university. I think it's different in America, something like go to school till 18?
Ok, he's not in school then. Jeesh, let's split some more hairs over this. In America, school is school, whether you are in Kindergarden or getting a PhD.
It's a joke. I always joke with the guys in my gym who are going to school about how they miss days because they have schoolwork to do. I'm not certain I'll make it; I just made the decision this is what I want to do and I'm working at it; the same way you determined college is your best bet. So basically, I was screwing around with you. Different people have different goals. But with a coach with the experience yours has, you have to expect that they might have the aim high or don't bother mindset.