Where do you live? Where do the children live? It may be less complicated then you think to get this worked out.
First.
We can't get a schedule out of her for out of state visitation
I wouldn't be trying to get a schedule out of her, I'd get it out of the court. And it would be VERY VERY specific. A good lawyer can help you draw one up. It wouldn't take a big production, just a motion to modify visitation. I would want definite language "the children will stay wit the father from June 1 through June 14. The father will purchase airline tickets with departures on June 1 and return dates on June 14. Mother will make sure that children are on the appointed flights or will be in contempt of this order. Father will return the children on the appointed flights or will be in contempt of this order." Put in some language about a fine or something for being in contempt. I wouldn't bother with the ASKING her when he can see the children, she apparently isn't good with that. I'd go for asking the court to declare it.
Second.
visitation that finally DID doccur is interrupted by dozens of phone calls to kids...promising them all sorts of presents and trips to Toy R Us "the minute you get back from Daddy"s".
Don't you have caller ID and an answering machine? Get a telephone visitation schedule as well. Let her know she can call the kids at X: XX a/p m and talk for 5 minutes each and that is it. Anything else, leave a message.
Third.
accidental took our mail
Thankfully she's far away now, so that shouldn't happen. But in the future, I'd limit her to the doorstep.
Fourth
She enrolls kids in extremely expensive schools and camps..expects my husband to pay without any voice in decisions and with no legal basis to do so..then tells kids they can't go because daddy won't pay.... or sets her self up as the hero and pays....sending the message that Mommy is the better parent because she buys them every thing and Daddy won't.
If she is going to play the money game with the kids, then dad is going to have to explain the rules of the game to them. Generally, I don't think kids should be privy to info regarding adult's finances, but there are always exceptions. Daddy should explain to the kids that he and mommy made an agreement. Daddy would pay a certain amount of money each month to mommy and that money is to take care of things they need. If mommy goes over her budget, then it isn't fair to daddy to make him pay for those things. If mommy wanted something special, she should have asked daddy and he might have been able to help, but daddy has a budget, too. Be calm. Be matter of fact. Kids understand a lot more than we give them credit for sometimes.
Last, in a nutshell, I think your husband needs a new visitation order. One with very clear language and ZERO ambiguity. If possible, one that also sets out consequences for non compliance. Hopefully a long drawn out battle is not the only way to deal with this very difficult woman!!!
Best of luck and God bless you!
Annie