Your son's behavior is a big concern and the drug issue, plus his going to far away at night with friends and getting stuck places sound like a scary combination. It also sounds like he does not abide by any rules of the house which are typical with drug use. When I say rules, I don't mean small, inconsequential ones, I mean BIG ones like not engaging in the behavior you describe and understanding that you can't go and pick him up 50 miles away. Very tough situation. It makes me think of Dr. Bradley's statement about "loving him to much to allow him to hurt himself." What he's doing sounds dangerous!
Did he start with the counselor? It really sounds like you need an experienced drug and alcohol/teen counselor to help you sort all of this out and that in addition to individual meetings with him and his counselor, you'll need family meetings.
Hope his meeting with the counselor went well. By the way, I like your name on here. Lord of the Rings fan I assume?
"The world is full of story shapes."