I can't answer many of the questions that you have posed, I think that is for you to decide as you see fit with wisdom. However I can say that I have come from a similar position.
I would say that pretty much without exception all my friends are drug users (of various types) and my closest friends are in a band, obviously this mean that when I go out with them I am surrounded by drinking and smoking etc. My siblings (one of which I live with) are also heavy Ganja smokers.
I used to be the same myself, however about 7months ago I cut all this out and decided that I should work hard on understanding and practicing Dhamma properly.
Maybe my current opinion will change in futuer, but so far I haven't seen it necessary to "cut" people out or to really "avoid" places in that sense. Since I have been practicing regularly and not partaking in these things naturally many of the connections I have had (with people and circumstance) have altered and lessened (or loosened). I see my friends less now than I did and go out less than previously, however I still see them and go out and have quality time. I have found that much of the time I spent was wasteful and not doing anything useful; I was simply trying to fill empty time which is now spent more productively. Think how often you go out just to "go out"
People haven't noted that I am around less no one seems to mind as it's not like I am blanking them, I still make the effort, I have simply prioritised and I have found that everyone respects this even if they don't agree or understand. I am sure this respect for what I do stems from them seeing the increased happiness, calmness and contentment that I have and that they are lacking. This is something that many people have made mention of and that I was aware of but evidently outwardly it's much more noticable
I won't lie. Not drinking does make spending time out far less bearable. Seeing my friends band is much more labourious than before but still when I weigh up the pro's and cons the pro's win every time. I reckon if people didn't drink they would be out where they are doing what their doing (so that is to say that they do drink to enable them to do this) It seems to be a way to fill time, to avoid the fact that they are standing around in the cold not really doing anything.
What I did was to take one step at a time, adjust yourself gently. You need not have everything planned and thought through analytically. Only right now and the choices you make here are the ones you need to worry about at the moment You know what works best for you and you know what doesn't. Be mindfull. See when and why your feeling occur and note them, see them. Then with this, as long as you have the sincere desire to practice then the rest seems (at least for me) to fall into place.
I don't want to give over the impression I am not without internal debate and dilemas (I still got many!) but with the first step taken the second (even if you don't know what it is to be particularly) seems to become clear naturally.
Once again this is just my experience. As much as we are all similar we do also vary. No one knows you like you know yourself, so do what you think and know is best. Listen to the Dhamma, understand not everyone must be a monk and just practice with sincerity. I feel immense gratitude for having had the opportunity to hear the Buddha's teachings. We are very lucky.
Here where a thousand
captains swore grand conquest
Tall grasses their monument.