Also sounds like he needs some professional help, like other users of this forum but we won't go there. I'd call Comcast and let them know what's up and change that to something that's not easily guessed. I'm not even going to touch the cars here.
You'll never find anything solid due to VPN. And like I mentioned before, those cases are almost impossible to prosecute. You've probably run out of options with that one. If he's using a VPN to log into iCloud, that's impossible to trace.
Beeping passing by your house sounds juvenile. I guess he's got more time on his hands than most people.
Did your girlfriend ever give him any passwords? While they were together?