1) He's promised to spend time w/his son...it's not going to happen any time soon. I wouldn't put much into his words right now...actions speak louder than words. He's into the "me" world right now.
2) Your h expects that things will remain the same and you will be right where he left you after the divorce and his crisis is over. Life moves on and so will you and your children. It doesn't stay still very long. He's on the wheel of mlc and it turns and turns and doesn't go anywhere, but you and your sons will grow and learn from this experience and will suffer the pain and heartache right now...he will later, if he wakes up.
3) While he is gone, sit down and put your proposed boundaries on paper so that you can be ready to implement them upon his return. No, you shouldn't be a taxi service because he does have a vehicle and can pick his son up and return him home. The most important thing is that once you've implemented boundaries, stick to them. If you waffle, he'll test you each and every time about them.
4) If he offers to repair things, it is because of guilt and yes, possibly, keep one foot in the door and keep an eye on you and what you are going and w/whom. If he does do the repairs, don't be around when he does them, i.e., go into another room, be less available. If he completes them, be sure to say thank you, just as you would if someone came to do them for you.
5) I wouldn't be sharing the SUV w/him. If you need the vehicle, then you need to keep it at your disposable or negotiate purchasing it from him in the settlement. You have to cut the ties a bit because he's not feeling the loss and it's giving him ample room for cake eating. You can always offer up one of the other cars or your h can do w/the two seater or trade it in, but it's not your problem while he's on the street and not living w/you. He's a grown man and needs to make some decisions about the type of vehicle he has in his possession.
6) He may be offering you less money for your expenses, but there's nothing you can do about the grocery, gas and utility bills. They are constantly going up and will continue to do so over the winter. You need to sit down w/a lawyer and get this taken care of and soon. He's trying to get you to cut back so that he has more money to spend on himself and his new lifestyle. Don't allow him to guilt you into reducing your grocery bill. Teenagers eat a lot!
7) Don't help him w/the divorce. If he wants it, let him take care of it. Get a lawyer and have him/her take care of your needs. You need someone in your court to ensure that you and your children get what you are entitled to. Your h is being nice right now, but when it comes to the actual divorce and what it will entail, his attitude will change the minute he sees what he will be requied to pay and/or do to complete it.
Fair? I don't see where he's being fair w/you and your children. Yes, he's being nice right now...but he's already beginning to tighten the purse strings and it will only get worse. You need to have something in writing and documented accordingly.
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.