What if the non custodial parent refuses to take the kids over the summer break, as stated in the visitation order? Won't he have to pay more child child support, as the payment amount was based upon the amount of time that they spend with him. Also, I have paid in full for a vacation during the time the kids are supposed to be with him, is he legally responsible to pay for the cost of my trip, if I am not able to go because Ill have the kids?

First, you can't force the NCP to exercise his visitation. However, if the support order was specifically based on his having the children for the summer, then you should file for a support modification.

As to being responsible for your vacation costs, you can try suing him, but I'm not sure you will win.

If he owes you more money will depend on the state laws, in some states, no it will not make any difference but in some states where they take your income and his income and the number of days each has the child, yes if he is refusing to take the children you can file in court to get the order of support modified

Since he is not required to take them, I doubt your lawsuit to make him pay for vacation costs would win, but you are free to try