1. Miniguns are part of Fallout lore as well as supermutants and plasma rifles.
3. Not long ago even smallest SG had mysterious ability to knockdown and knock out you. At that time man with leather jacket with hunting rifle that both cost aprox 1000 caps was able to take down man in Brotherhood Armor and Avenger Minigun (let's say 20k but it's much more) in 3/4 of situations without getting hit. Even then people were comming to forums and whining how miniguns are bad because they kill you so easily. Also someone actually invests his time to get this 5mm AP ammo. You spend over 20 minutes to get 200 5mm AP ammo which gives you 5 bursts with Avenger so let's say you can kill 5 people (thought it happens very rarely and most likely you need two bursts to kill a man even on bluesuit). During 20 minutes Small Gunner can craft around 100 .223 FMJ ammo and let's say he is able to kill with that ammount at least 10 people (I am not even counting instakills). I think it's kinda balanced and going to boost SG more is... hmm at least werid concept. Small guns are easy to get, varied and you can get ammo for them easily. Big guns are very few and the weakest gun that is able to do some damage is M60. Getting ammo for it is painfull... you not only need advenced gunpowder but also special terminal to craft it. Eh.
As for getting miniguns or any other kind of weapons/armors rare and hard to obtain... as long as you can get killed by instakill even in APA I dissaprove.
2. and 4. We live as outsiders in tents - middle of nowhere. Later we form gangs and live outside towns in some wrecked buildings. Who lives outside cities? Raiders. I think that's one of major game flaws.
4.A - Sounds good. Not much to add.
4.C - Travelling between towns and earning caps for selling goods (brahmin hides, gecko pelts) for profit? If you mean that in some town you get higher price for gecko pelts and in other lower I support that.
5. Everyone involved knows about diplomacy between gangs. Rest of players isn't interested in PvP so they don't care. I don't see problem with that and I don't see reason to inform/bother non-PvP oriented players.
5.A - Two enternances that you can choose from preview and one of them only visible/accessible for members. Why not?
5.B - Devs are against it. I wouldn't mind that.
5.C - Most likely devs will not like this idea as it will drag people out from towns
I think if devs would rethink whole system that they made and make changes it would actually work out but... it would require lots of work in lots of game aspects (look at my reply for 2. and 4.).
5.D - Not needed.
5.E - Interesting. Needs more thinking.
5.F - I don't know. I would like to see more examples to how it would look and then I would make up my mind but as for now I don't like this idea.