Duplicate functionality of a custom Zencart plugin for use on Magento 2.0

I have a Zen Cart plugin that was custom made that has this functionality: 1) pass on the order total and a modified product description that is for one product that includes the order number to [login to view URL] shopping cart 2) check for completed payment and update the order as paid The old plugin had parsed emails to confirm payment, however a better solution could be an IPN call from the payment processor to the [login to view URL] service. Zapier can receive, reformat or forward any IPN info using webhooks, similar to as discussed here [login to view URL] 3) The old zencart plugin forwarded the data to mals-e and the customer left the website to complete checkout on the mals-e website. This time an iframe should be used so that them did not use an iframe, however on the customer enters data on the mals-e website within the iframe, within Magento. 2.0