Hmm. It's interesting reading this because some of it is true of my mildy dyspraxic ds, and some isn't. I think we're in a wide bracket of characteristics here people. Your son walked at 9 months Ingles! Someone elses son can draw beautifully!
The best thing I've found for controlling the behaviours which are basically a sign of stress - frustration/ anger, chewing, anger again, negativity is to get REALLY REALLY eye-wateringly organized.
You'd be amazed how much of a difference it makes, and how it reduces their stress levels.
Lists on the door of what they need each day, shoes in the same place, encourage them to say out loud what they need and check it against the list.
Talk about the day ahead - encourage them to talk about it too. In as painful detail as is necessary.
If younger - we had this - a v. jolly helpful note in the toilet to remind them what order to do things in: pants down, pee, pull up trousers, wash hands, flush loo.
That's helped us. DS2 is actually really, really wonderful. He's funny and smart, and messy and distracted and sweet and thoughtful and a bit out to lunch. I adore him. He's not bad with friends, and has found v. impressive compensating strategies for the sports problems - ie. he decides to be the referee at playtime.
Also he's got a great sense of humour - you need to USE this. I once fell off the bed laughing as ds2 described to me in toe-curling detail - and with great amusement - how he completely failed to hit the ball in an open goal. It's okay! Don't wince about it.
Find what they're good at, go for that. It increases confidence. My ds2 likes singing for instance.
DS2 is nearly ten, and lots of his sensory stuff is much improved. He'll chew now, sort of. And wear clothes! Go to parties - noise isn't always such a problem.
Give him space OP to be in his room, to order his universe. The rest of the day, and other people, can be a huge strain.
Encourage him to be himself.
btw Ingles - ds1 was a ticker - and he's not got a dx of anything! He used to hand flap, roll his eyes, do all kinds of odd things. He's nearly 12 and he seems to have grown out. He used to do it when excited in particular.