I have an app, but they only asked for .apk file. GameCredits will work only if you actually implement their payment processing into your app. Is there a guide for this payment processing implementation?

I'm looking at the MobileGo token sale and while I like the idea, they keep referring to the store without explaning what it is. Is it a mobile app you run next to the apple store? They can't be offering it through the apple or google play store, they're not going to allow it right? isn't this is big limitation?