These FAQs are specific to the API and not to the Infusionsoft interface.
App Partner
How Do I become a Partner
After you are done building your integration you can submit to become a developer partner and listed in the marketplace here
Does it cost to become a Developer Partner?
No the program is completely free. You just need to build a working integration.
Who is the Developer Program for?
The developer program is for any application that wants to create an integration with Keap and advertise that integration.