Your ideas are very thorough and well researched - I hope the developers take note.
I also agree with your comment about the limitations of the Roadmap. Apart from not being able to upload visual explainers, it's a lonely place with no-one else interacting with user ideas. All you can do there is vote not-important>nice-to-have>important>critical, and add your voice - but you can't see other people's valuable points of view on the ideas. The idea effectively dies unless someone from Epic deems it interesting enough to include on the list.