Payment Gateway Integration and Implementation

Need someone who knows everything about Payment Processing gateway from inside out. Planning to start a service (let's call it [login to view URL]) like Paypal / Xoom / Transfast etc. Using this service, third party websites can checkout using [login to view URL], like they do now as checkout using paypal or amazon pay. Or they can simply send money to friends or family or businesses etc. I have source code for a Payment Gateway but not yet deployed. As I need some modification in it before I launch it and configure it to work with banks too. When you respond, mention "Payment Gateway Expert" in the proposal at start, so I know you actually read this and are not submitting for job without understanding it first. Responses without it will be ignored. Mention your hourly rate for long term association too.