With mine at this age, most things are a discussion and habits rather than having any firm rules, but it can depend a bit on your teenager's nature and your household.
We don't have a blanket curfew, it's discussed on the occasion and I'm generally more interested in if they've planned out transport than time.
We regularly discussed tactics for alcohol as part of harm reduction conversations whenever it comes up. My only firm rule there is I don't give alcohol I'm not supervising, and my kids know that their father and I would prefer they have their first drink with us.
It would difficult for my teens to be home alone long with how our household is set up - I can't remember the last time all of the adults were out of the house at the same time for more than an hour, and even then their siblings are here who will with glee say what's happened while I've been gone.
We generally allow my older kids' social circle to be here, regardless of relationship status, as long as they're amicable. Our rules since they were small are any guests upstairs means doors are open, they are not to allow guests into my room or the lodger's room, and because all my kids share rooms, any sleepovers happen in the living room, nearly always when their father isn't working so there is a parent awake.
We have a TV in 1 room and have a rotation of who is in charge/what's going on in the evening. On nights my teens are in control, that ends at 10 unless it's a special occasion. Generally, the older teens go up before then, they can do what they want in their rooms as long as it doesn't wake their siblings (my 15 year old doesn't take her phone up, my 17 year old has been using it as an alarm for the last few months with no issues yet), but sometimes the 17-year-old will stay up while my husband and I watch/play stuff before I go to bed & he goes to work, particularly if he's roleplaying online.