I have read the entire "script". Here's my take on it:
1. He doesn't want to put the kids on his insurance because he would have to pay more for the "family" plan vs. a single plan.
2. I found it quite interesting that he hates the house, but will not do anything to help you get it sold...however, he then wants it sold and for you to sit on the money for a while. He is still trying to control your life from afar.
3. As for the dealership having your number...I went through that myself. They do this to aggravate us in a passive-aggressive way. Yes, he could have had the car serviced in his town, but he preferred to have you wait on him and play taxi.
4. File your taxes separately and leave him to his own mess. You can't keep taking care of him. You are not his mother. His tax situation is of his own making.
5. Going into the systems and looking at your accounts, especially your business account is not good. It's good that you changed all of the account passwords.
6. My xh said he was never ever coming back and he didn't. Your h saying that is telling you that in his mind, he is absolutely sure he's not coming back and he wants to end it, but he doesn't have the guts to do it all himself. I wouldn't look for him to file any time soon, if ever. It looks like you will have to do the heavy lifting if you want to cut the ties w/him.
7. He doesn't think that you will call his bluff on anything. He enjoys playing w/your mind and emotions.
Your h is trying to control and manipulate you and your kids. In the back of his mind, he wants to keep you right where he left you in case things do not work out w/his women and financial standing. I know what I'm about to saying isn't DBing, but you've put up w/enough nonsense from him since he left. You've attempted to be the nice person in all of this, now it's time to start thinking about your and your kids and leave your sorry h out there. If I were in your shoes, I'd file separately and leave him to take of his own taxes. I would begin to separate everything in the way of credit cards and any and all financial dealings. I don't know about in your state, but in my state, after two years, you can file. Of course, had my knuckle head stated he was committing adultery, he could have filed within a year...but he didn't want to look bad in court or have that on divorce decree.
Seriously, this guy is pushing for you to do all of the heavy work. Try to remember...the more you try to rationalize w/him the more irrational he will be in his passive-aggressive way. You can't push them out of limbo because they are so stubborn and it gets old w/the lbs very quickly and we tend to lose sight of what we want done because we are focusing on their crazy making behavior. Turn your focus back on what is important right now...your taxes and keeping your accounts safe, secure and private.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.