Well first of all the people best able to decide that would be the people living there. I can't tell them what they should do for all scenarios, and furthermore you can literally WHAT IF just about any idea to a stand still. If it is something new that hasn't been done before sometimes you have to take a leap and learn, and only when you are in the situation will things you and I cannot imagine come to mind for them. If it fails then they will have tried and hopefully learned, and unlike the Marxist, Socialist, Communists at least then they will hopefully not keep trying to do the same thing over again without truly paying attention to the failures.

With that said. Voluntary does not mean people cannot defend themselves or each other. The Non-Aggression Principle simply means people will not initiate violence. They will defend themselves. If someone attacks then they can attack back. If someone kills there is no reason they couldn't form a posse or go after the person themselves, or contract someone. As long as it is within the constraints of the Non-Aggression Principle and is not initiating violence but is instead responding to aggression that has already been initiated then it should be fine.

A lot of the time people mistake NAP as being the same as passiveness. They are not remotely the same. I for example try to follow the NAP, but if anyone attacks me I'll do whatever I have to do to stop them and I'll likely be quite brutal.