If youre looking for software with GUI, EAC is considered Gold Standard but not available for Linux. I can recommend FRE:AC though, works very well!

/r/homenetworking /r/homelab

This subreddit is about discussing selfhosting software. Not about which networking gear zo buy

Not that I know of. But maybe also ask in /r/musichoarders

I dont think this exists. Maybe you can use an existing server and player and automate it with home assistant