2 tasks: coordinate 2 plugins / Insert a system billing -- 2

Hello, I am looking for a developper to make 2 tasks for the multisite Wordpress: 1/ Need to coordinate 2 plugins: We use Pro Sites plugin from WPMU Dev and Gravity Forms. We need to use Gravity Forms for the user and site registration. But basically the registration is done with ProSites that uses the Wordpress refistration itself (If I understand well) . That means that we can make only one kind of registration. But Pro Sites offer the possibility to have others plans and we want to offer these as first registration too. So we need to coordinate the forms ID (Gravity Form) to the Pro Sites plan ID For example: Enterprise Plan form should match the Pro sites ID of this plan and creates the website as Enterprise. 2/ Need to integrate a a billing/receipt solution to the Wordpress MU. Our customers will need to have an invoice. For example: one customer subscribes to the Enterprise Plan monthly, he should be able to dowload the Invoice or to receive it by email each month, as this is recurring payment with Stripe or Paypal. There's some invoice/bill plugin on the market but no choice is done yet. Thank you for your offer.