I think your concerns are reasonable and you're response up to this point has been fair. When it comes to neighbors, I generally try to follow the Roadhouse Approach:
be nice until it's time to not be nice. Video surveillance is a good idea. Call the cops on him and let them deal with it. When you are talking to the neighbors go out of your way to make sure they know that you are just a regular joe doing the best you can to get along with everybody. More people who are sympathetic to your cause the better.
Worse comes to worse you could always catch one of the kids and brand them. If that doesn't work, brand another one. Sooner or later they'll get the point.
