If you mean retroactive support (i.e., support for a period prior to the entry of the first order), probably not. If you mean past-due support (i.e., support due pursuant to an order and not paid), there is no statute of limitations on collecting that.
yup
They may, by contacting the child support agency with jurisdiction for the necessary paperwork. You must be willing to forgive past due child support, not just stop the agency from going after them at any given time. Or you can petition the court for a hearing regarding your wish to forgive back child support.
I doubt there were many child support laws back then. Normally, only the custodial parent of the child can file for child support, not the actual child.
yes
Yes, they can. n
The duty of support continues until a child turns 18 years of age. A court may order support up to the age of 20 so long as the child remains enrolled in secondary school and is making substantial progress toward a diploma.
Yes.
your State's child support agency
The parent must pay any arrearage, yes.
No, you are not responsible for their back child support.
what if your done with current child support but still owe interest for back support.
Yes, if a parent owes back child support, they will have to pay it until it is zeroed out even when the children are grown. The age of the child does not affect back child support at all.