The interstate visitation rights act gives great information in the area of this question. http://www.law.upenn.edu/bll/archives/ulc/icv/chldvsit.htm
No
Take it to court.
absolutely
In the state of the child's residency. see links
Yes, if he has visitation rights or shared custody, she will need his consent.
Yes. However, if the visitation is no longer practical, one of the parents may need to file for a modification of custody or visitation.
Leave permanently, no. That would violate the visitation order. To move would require his and the courts consent.
The child may visit at any age if a court order for visitation is in place. If no such order exists or visitation has been terminated for any reason, the child can visit their parent when they reach the age of majority in their state, 18 in Colorado.
Regardless of what state your child lives in, yes you are required to pay support, the case will become an interstate case. You will send the support payment to the state in which the child resides and the money will be disbursed accordingly.
YES, if the summer visitation is written in the divorce decree.
Not if there is a court order for visitation or shared custody. She would then need your permission and the courts.