states have individual laws
see link
Yes your child's dependance on your support does not change because you have a disagreement with your ex.
In almost every place State Province etc. If you make it you pay for it, maintenance is what it is maintaining the care of the child regardless of your involvement with the child, if you are the biological parent then you need to pay for it's care and well being.
Through court actions, but not on her own.
A judge can stop anyone from seeing your child including you. If a parent need to be kept away from a child the judge can see to that but there has to be good reasons to. Anyone else is up to the parents to decide. Some states have rights for grandparents to see their grandchild. But that is as far as it goes for relatives.
When the child is adopted or have reached 18 or 21 depending on what the child support order says and state law. Even when it ends at 18 it can be possible to ask for support until the child is 21 and finish college.
If you want to fix your child go to the plumber's house (child maintenance)
No - you should only have to pay what has been stated. Her having another child has nothing to do with your support payments for your own child. I would definitely think about seeing your lawyer.
Pay your child support through either the courts or the State disbursement unit. DO NOT give any money or anything else to the obligee unless you want it to be considered a gift.
You can find help by arranging child maintenance yourself or through child support agency(CSA) or child maintenance service. These organizations will help you to work out how much should be paid which they will also help you to collect the payment.
Depends on the meaning of "seeing".
Back dated to what if it's being stopped?
Depends on your state.