Create AP Payments (ACH, EFT, Check, Manual, Wire) through API/Interface

We create invoices in our oracle EBS R12. But as we are child unit of a larger company, they make all the payments via PeopleSoft and send us a EDI file. So now, we want to develop an inegration application using the API/Inerface to apply all the payments for different payment methods in our EBS system. Firstly would it be possible to develop an application using API/Interface to solve the problem.
Secondly what interface I should be using for payment not only for check payments.
Thirdly whould using AP_PAY_INOVICE_PKG (which is not a API/Interface) will solve the problem.