Don't panic and think ahead all at once.
Medication is a discussion you'll have if and when he's diagnosed but I think it can be enormously helpful. If it does come to that, you'll have support with how to approach it and what the safeguards are. It's absolutely not a case of just medicating and then you're left to it. There is a lot of crap talked about medication but it's not taken lightly and it is actually the most effective treatment for ADHD.
To me it sounds like his symptoms are quite severe (compared to mine) as it's affecting his education (in terms of his behaviour alienating him from teachers) and friendships. So some kind of management should help with that and it's best if you can get this in place before his self image totally goes wrong.
You can put things in place to help him, but be wary of adding so much scaffolding that when you take it away (e.g. he moves out) that he just falls down. What is more likely to help him is encouraging him to find strategies which help him, and supporting him with things he asks you to help with, rather than doing it all (especially the thinking and figuring out what would work) for him. This will help him to learn how to develop healthy coping strategies rather than coming to rely on unhealthy ones (e.g. being the class clown because he gets into trouble just for doing normal things and at least this way, he also gets positive attention from his peers, which he might otherwise find hard to get).
I think for me home ed would have been a disaster as I needed the structure of school, and if he wants to continue in education then a very "typical" path (e.g. school, sixth form, uni) would be the most beneficial, nothing outside of that normal path, unless he wants a different route entirely. But that's a long way off.
Emotional disregulation is absolutely associated with ADHD, as keeping emotions in check is basically part of impulse control, and ADHD gives you poor impulse control.
The very best info I know about ADHD are the talks on youtube by Dr. Russell Barkley. Nobody understands it like he does. They are long but extremely worth it. You can't see the slides on most of the videos anyway so I recommend to just listen to the audio while you're doing something else. You might prefer to wait until you have a definitive diagnosis, so until then, the key words you want to google are "ADHD executive functioning". This is the best and most up to date understanding of ADHD and gets it right, IMO - it explains why certain things are hard and helps with understanding exactly what is going wrong so that you can help your DS to put the right things into place.
Another good youtube resource is the channel How To ADHD although this is mostly aimed at people who have ADHD, you might still find it helpful.