1) I agree there should be an undeground. Whether it's open PvP, that I'm not going to argue about here.
There are undergrounds that was not the point. I am talking about an hideout chance for badguys (lockable doors and such). PvP would be on becuse of the realism in mentality in that place (I mean c'mon... a place full of criminals, wackos etc...). F.ex Eggbob McTavern is new in town and takes the wrong turn to a dark alley with 20 shady figures... what happens? He walks by them and nothing happens. In this area with PvP he gets killed. THIS IS MY HOOD, YNNWN! After he trains himself stronger he can confront the ppl there but still he must remember that this is where they live.
3) Home field advantages are player knowlegde and shouldn't be introduced into the game mechanics. You have an advantage in areas you know because you know your way around better. That's a player skill. If I defend my house in real life, I'm not getting +20 strength against any burglar that I encounter Tongue so basically I don't think this is a feature that is needed in this way.
Think about this: Someone invades your home your daughter is sleeping upstairs what happens? Most of the ppl will try to keep their daughter safe at all costs which raises adrenaline which gives strength. Someone attacks your village you know certain things that make you more agile as you don't have to use your perception as much as a fella that sees 20 things that are new to him and that his brain needs to register. Will has a great deal to do with these things even in RL. This setting wouldn't be applied on all places ofcourse and also this would keep many from fighting in cities and/or public places (talking about noobish ppl mostly EDIT: Like me). In real life you don't create yourself and you cant measure your agility with points. This idea was mainly because now, you don't get advantage fighting from higher places etc.
I would say I'm such a patriot that if someone tried to invade my home i'd get pretty berserk. (In real life you can increase your str, perception etc for just a while. Usualy with drawbacks such as feeling weak after or shaking)
Ps. I didn't say CRIME was easier I said being EVIL. I can kick anyone that I meet or steal most stuff but I can't help everyone or retrieve everything. Look at the world... what's happening? Who is getting richer and richer? who is winning...? the good guys?