Being medication compliant was one of the major carrots we used so Miss KT would be allowed to drive. I read somewhere that a teen with ADHD and unmedicated is emotionally 12. Who wants a 12 year old behind the wheel of a car? That DUI would worry me. Does he own the car, or do you? Look into the liability and your financial responsibilities, because an accident, with him under the influence, could absolutely destroy you financially.
The respect and helping out around the house - I agree, these are necessary. What are the consequences if he chooses to ignore your rules? Are you prepared to bounce him out if he refuses to comply? I'm guessing you're in the United States, where he is legally an adult, whether or not he behaves like one. You might want to look into the steps required to evict him in your state, just so you have that info if he refuses to leave if you ask him to.
The different avenue for treatment sounds promising, but again, he can legally refuse treatment if he decides to. The self care and sleep habits...again, he's legally an adult. You really don't have a lot of leverage here. Not trying to be depressing, just realistic.
Please make sure you have all your ducks in a row and that you are prepared to follow through on any consequences you impose.
