You know, he's got some stalkerish traits in him. At this point it just sounds like he is being stupid, but stay alert. I don't like to say it, but I could see him turning dangerous, to you, the kids, or any "friends" that you might have. Just stay alert!
When he asks about cars at your place, don't tell him. You could start with "I don't remember", or you could, at some point, move to, "It really isn't any of your concern." Mostly because it isn't!
