On point 4) I would say that there are good local audio players. A good audio player should support most file formats. Definitely the ones that are "findable", mp3, flac, ape, ogg, etc. Bonus points if it supports full-album flac with cue describing seperate tracks. For some reason "certain" sources like to distribute like this. On windows I use foobar2000[0], on mac Cog[1], and on linux honestly most players support standard features. If you're on an os that is more functionally compromised like Android, iOS, etc., you can always use VLC[2]. Note that the flac+cue thing doesn't always work properly and on foobar you have to find and install an extension to get it to work. Foobar is really nice as it support batch processing nicely. Also about the flac+cue thing, in foobar you can easily convert to separate tracks. It also runs fairly well in wine.

[0] https://www.foobar2000.org/download

[1] https://cogx.org/download.php

[2] https://www.videolan.org/vlc/