Does my child need to have surgery for his PDA if the initial medications didn't work?

Maybe. The fact that you say medication didn't work makes me assume your child is in the nicu. In this setting the PDA usually has an impact on the baby's ability to breath so the PDA needs to be dealt with. In older children pda's can be closed non-surgically in the catheterization lab, but if your baby is very small this option is not available and tying off the PDA at bedside can usually be done.
Depends on situation. Premi's often have pda's that complicate treatment by diverting calories that would allow growth and healing to fueling the extra blood pumping work.After medication fails, you have to chose between waiting an indefinate period for it to close on its own (risking the occasional complications of ICU care) or closing it surgicaly to get back to growing.Each case is unique.
Depends. The need for a procedure depends on the size of the PDA and your child's symptoms. If they are not gaining weight, or having significant breathing/other problems, then they may require surgery early on. Alternatively, they could have it closed at a later age if they are doing ok. Please discuss this with your child's cardiologist.
Depends. It depends on the size of the pda. The need for oxygen. The size of the heart. Your neonatoligist can discuss these aspects with you.