What kind of tidying up? All corrections you do should consist of optimizing/correcting folder structure, file names, and embedded meta tags.
I would avoid making any edits directly within Plex, except for playlists and collections.
I’m not sure what you mean. The Plex Dance is specific to the danced items, not the whole library.
They certainly do. Ensure you have debug logging enabled in the server settings (but not ‘verbose’ logging).
