J.,
Here is a different perspective. I am both the x wife and the stepmom. So I can honestly say that I have worn your shoes. And I have walked many many many miles in them. And I know that it is very hard. My hats off to you for finding some advice. It wasn't available to me when I needed it.
First the child support issue. Contact the Attorney General's Office they do not charge for enforcing the Child Support. Granted it may take a while, but they will have it deducted out of his pay.
Secondly, the Step Mom, Now my daughter is 14 and she has "played this game before." Your daughter is playing a game that she will lose if you stick to your guns. By saying that I mean, this is new territory for your daughter. Having 2 moms can be difficult for kids. There is ALOT of confusion. ALOT of different rules and ALOT of playing mom and dad against each other. Right now Step Mom is trying to get her to move in with them so she is being nice to her "buying her love." So after a while (it could take 1 month or it could take 1 year)It will change with the Step Mom. If you let your daughter go live over there before she is 12 then she will see that the Step Mom will change. By NO MEANS am I saying to let her go live over there, I am saying IF.
Now here comes the different persptective, No don't go through the Step Mom for the issues about your daughter that's for you and your ex-husband to deal with however, INCLUDE her on it. Kill them with Kindness. When the Step Mom feels included and no longer sees you as a threat she will stand down. If you put the Step Mom down it will hurt your daughter. If you have something negative to say about the step mom post it up here or write it down in a letter and burn it, Or talk to a friend that you have that won't repeat what you have said to anyone and out of your daughters hearing distance.
I am sure that you are starting to feel that your daughter just may love this Step Mom more, but remember YOU ARE HER MOTHER, she will always love you more, and right now she is testing you and her dad, as well as her step mom. Whatever you do, don't try to compete for something that you already have. Your Daughters Love. Again stick to your guns. If need be, call a meeting with your ex husband and his new wife (if they come great). But let them know that ALL of you need to work together, with consistency. My ex still doesn't work together with me concerning the discipline of our kids. But at least I can say I tried. And your daughter will adjust to the two different sets of rules or the "separate Lives". Just take a deep breath and breathe. Go take a Bubble bath, scream into a pillow, what ever you need to do to release this anger. Keep in mind your daughter is adjusting just as you are.
L.
Some of this advice was given by my daughter who has been able to shed some light onto the child's outlook.