Not technically. Child support is for a custodial parent to support the child. Check your state laws.
no
Yes a child can sue a parent for unpaid child support if there was a child support order.
If you're in the US, no, a child cannot sue his parent for child support (payment for child support is not due to the child).
If you are separated from the other biological parent, and he is a minor, then you simply sue the other parent for monthly child support.
Absolutely not; the child doesn't owe the parent(s) anything.
no
If they can establish the stepparent as a primary support in a parent/child relationship.
Only if the obligee parent releases the claim or is deceased.
No. Your custodial parent must file a complaint for a child support order in the family court in your jurisdiction.
No. If there were arrears in this case it was owed to the custodial parent. The child does not get child support or arrears.
No, the child can not. The other parent could before the child was an adult. The money goes to the parent to use for the child and not directly to the child.
Yes, as an adult you can sue a noncustodial parent for back child support. However it is a different story if the noncustodial parent has never been ordered to pay child support. You can still sue them for a percentage of their assets. I am currently working on a case in which my client is sueing his father for 15 years of back child support. Any divorce lawyer can handle this case for you.