Hi Mike808 ,
Some answers for you in the order that you asked them.
1. There is a policy in the works that we are planning on adding "soon". Keep in mind though, that this won't prevent users from downloading the apps from alternate sources and installing or running them so this is more or less just security by obscurity.
2. There is no direct mechanism in Intune or Windows to trigger this for a management tool. The Store itself is responsible for updating UWP apps and will do so based on its own internal rules. Note that the story is slightly different for Store-based Win32 apps.
3. Soon. Keep in mind though that Intune features in public preview are fully supported in production and we fully intend for customers to use them in production.
4. For parity between the community repository and the Microsoft Store, that's up to the vendor or publisher of the app and is not anything that we control. If you want an app in the Microsoft Store, whether it's in the community repository or not, you should contact that vendor or publisher and encourage them to publish their app to the (one and only) official, public repository that is accessible on every Windows device. The community repository is just that, an unofficial community-based repository.