I only have slskd, so I’m not sure if it’s different, but folder structure should have artist > album, but outside of that it doesn’t matter much. My folder names all contain musicbrainz ids for use in jellyfin, but I’ve had plenty of uploads.

On the readarr front, check out chaptarr. It’s currently in a closed beta, but it’s looking like a great replacement.

You’d think. But nope.

They may have an irc. I’m honestly not sure, and there doesn’t seem to be any information about it outside of the website, unfortunately.