since there really isnt a push notification for Android... How do you let your user base know to update their app?
This is part of the Play Store settings which each and every one of your readers will have set up to their own choice... I believe the default is to notify when updates are available though
If i submit a new .apk to the store, will the android user base be notified that there is an update?
That requires to go through the Marketing Cloud - See what's new in 2016.12: What's new in Experience Manager Mobile
The Analytics Mobile Apps contract allows for this - see more details at Analytics in AEM Mobile