I am trying to simply member registration process for my members who register using Janrain Engage (Social Media login) with the s2 member paypal pro form. Is there away to connect the registration process with the payment process for the different member levels.
I don't know, the pro-form already registers the person as part of the payment process. We haven't integrated it with Janrain yet. I'll email Jason, the Lead Developer, in case he has more info on this.
I would recommend the Remote Operations API that comes with s2Member Pro. Or, try s2Member's API Notifications (available even in the free version). These are ways in which s2Member can communicate with other 3rd party apps. Short of that, you can always build custom scripts that make use of core WordPress or s2Member functionality. See: viewforum.php?f=40