(1) Can you give me some boilerplate/generic code which I can modify, that allows me to add a new payment gateway to ProSites? I basically want to add some payment gateways--> FastSpring and Moneybookers, to ProSites. If you can give me some starting code (which I can use to create such payment gateway plugins) that would be very helpful for me.
Another query related to above point-- as per current ProSites payment gateways--> can a user cancel his Paypal/Stripe subscriptions through ProSites? Or does he have to go to the PayPal/Stripe site and make changes to his subscriptions there directly?
(2) Currently in ProSites-> a user can purchase one premium plugin at a time--> I want similar functionality to be available for themes as well--> so that the user can purchase one theme at a time. Please let me know how to implement such functionality in ProSites.
Finally, for both the points above, ideally I would want my changes to work even when ProSites is updated periodically.