As of April 12th, you must go to Progress SupportLink to create new support cases or to access existing cases. Please, bookmark the SupportLink URL and use the new portal to contact the support team.
Kinvey can track usage that way, but doesn't do that.
An active user is defined any user that makes API requests during that month. So, you will be charged for active users (registered users that access the app during that month + one hard-coded user).
If I understand correctly, you want to allow users can browse freely without logging in. But, a user must signup/login to do bid or buy.
While using Kinvey, if you refer to the documentation - http://devcenter.kinvey.com/android/guides/users#ActiveUser, you will find following salient points: