Mines 16 and also has a physical disability.
He's fab 
He does have his struggles. He still finds people hard to understand but he's now aware he can't read facial expressions and body language so can find his own ways around this.
He doesn't go out with friends and is too anxious to go out alone.
But he swim trains for hours (13!) a week and is aiming for Paris 2021 para olympics.
He had support throughout school and had some really difficult times. He had some cbt through camhs and sadly was a target for bullies.
I always (at camhs suggestion) allowed him a day at home if he couldn't manage it. I rang him in sick. But the advantage of this was he felt able to go in because he knew we all would support him if he needed to come home.
He's an amazing memory for facts and can talk at you using language and words I couldn't even spell to Google the meaning of - but simple everyday conversation isn't natural.
However he is the most amazing polite mannered boy and has an array of learnt phrases to talk to you.
Everyone gets asked how they are, to have a nice day when we say goodbye etc. He may sound like a robot when he says it and only says the same things everytime but he without fail melts the hearts of adults who find him charming!
Yes he gets very wound up at times. Sometimes just a word can trigger him getting wound up and then he'll leg out frustrations about a whole host of things.
The other day I stupidly mentioned it was officially day 1 of the Easter holidays. He finished college last weds. Which led to a whole 10 minutes about how it wasn't a fun day (well no kid - you aren't at school now!), hed had 2 exams and the last one was English. Onto how he thought when he left school he'd never have to do English ever again. Onto how it's a pointless subject and why do they spend their education reading, learning and writing what they think quotes mean from famous authors.
Which ended in
If they want to know what Shakespeare meant when he wrote Macbeth why did t they ask him before he died what he meant 
He's actually hilariously funny without often intending to be.
My biggest advice is remember you will be his biggest advocate and be fair to people who don't get it right - I always say "do you think I got it right first time or every time?" Who at least want to and try to get it right.
Give people advice that will help him ("what I find works in x situation is .....") but also don't knock down people who tell you that when in a different situation they actually do x y and z.
After all they are still kids who will try it on if they can 