It all may depend on the wording of the divorce and support decree - and/or - the wording of the law in the state in which the support was granted. You will have to check the wording of your documents and wording of the support statutes for the state involved.
Yes, the court will terminate child support.
Termination of parental rights does not terminate one's child support obligation.
because the custodial parent passed away,
by paying it until it's paid off.
I suggest you consult with the other parent and an attorney on this. However, keep in mind that terminating parental rights does not terminate one's support obligation.
No, a mother cannot cancel child support on her own. Child support is a court-ordered financial obligation to support a child, and only a judge can modify or terminate a child support order.
Make an official request with child support enforcement. see links
Age 19.
You can't terminate your obligation to support your child. That type of order must be decided by a court and only when the child is being legally adopted such that another parent will be responsible for the support of the child.
I'm not familiar with Canadian law, but moving the child out of state in the US would not terminate support.
Termination of parental rights does not, in itself, terminate child support.
Yes, until/unless the child is adopted. see links