Hiya khl.. im 36 now but from 14 to 18 or 19 i was having weed litrally everyday. In the end i hated the stuff. It ruined me progressing in school. But ive done good now.
I guess he has to want to stop. I did a calender and ticked each day off i hadnt used and took up the gym and running. That helped me a lot then. With the drinking ive never been a big drinker. I guess he really does need to go to an AA meeting.. its ok for him to say ill have it twice a week, but if he is an alcoholic thats just not going to work.
Try and persuade him to go to a meeting.