"waive" ... Yes, with the court's permission. She cannot waive support due the State as reimbursement for assistance provided.
yes
If you mean, the child's mother (ex-wife) has custody, the child's father (ex-husband) is obligated or potentially obligated for support.
no unless he can not support the child
No....
Yes of course if he has custody.
No.No.No.No.
Yes you can.
guardian of what?
no
Not in the slightest.
Your current wife is not responsible for your children by your ex-wife.
no