Having separate communities around the same topic could be a good thing? This would mitigate the hivemind phenomenon caused by the voting system with a large user base. You could discuss with like-minded people but keep the opportunity to read diverging opinions when you want/need to.

I would also like "hubs" on topics to discover communities, but a common feed might be counterproductive.

Yes, you can click on the "Toggle sidebar" button on the top right

Did you try to disable "Fast Startup" ?

By default, Windows does not do a real shutdown anymore. It closes the user session and hibernates, to speed up the following start up. As a consequence, the Windows partition (and EFI partition ?) are not properly unmounted.