While it doesn't directly address most of your questions, check out some of the resources available under the PowerApps Center of Excellence. It helps you craft some governance and automation around apps so you can let people be creative, but keep things organized.
One of the single best practices: a flow that automatically add a second (usually IT dept) owner to all apps. This gives immediate visibility to the app and helps you get resources to new app makers as they adopt.
Some of your other questions may make good suggestions for future functionality - consider nominating those on the Community page.
Hope that helps,
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