I have 3 teens 17, 15 and 13 and they are hugely different in how they respond to stuff.
I think hobbies eg piano have to be a choice, so i would let him give that up once the current paid ones have finished.
friends - well in our house it is friday and weekend only, weekdays are homework. (except I will now contradict myself, as dd1 does band, scouts and a club during the week, but keeps on top of everything)
I have never checked their homework, but then they have always done it. As soon as I found out dd was getting behind, I checked for a while, which basically meant I took her phone until she had done it! Then we made sure there was space for it to get done.
Chores - nag, nag and nag again. But they ave alhways had to do some, so I would say no TV on a Saturday til their room was tidy etc. Now it is do it or hand your ohone in.
But I don't make them do much. They are responsible for their own room, including changing sheets, for ds I had to say - no pizza on saturday evenign if you haven't done your sheets, which led to much huffing and grumpiness, but got there in the end.
They do clear the table and pack the dishwasher, and empty the clean dishwasher between them.
But the biggest message is really pick your battles, decide which things are your boundary lines and be prepared to stick to them, and let other things go. Eg dirty dishes muct come downstairs, but if they choose to live in an untidy room, well, so be it.