I just read through your thread here - first, sorry that you and your kids have had to go through all this....
I am sure that I will have something more insightful to say later, but one thing I want to point out:
If cell service stinks at her place, she has no way of getting through to 911 in the case of an emergency. Have it written into the decree that this is required, even if you have to throw the $40/month for her to have a phone. And set a time that you will be in contact with the kids on a daily basis (we use 7 pm, give or take a little - the kids expect and appreciate the routine).
