Used workstations are great for home theater purposes. I’ve got a Dell SFF on one TV and a Lenovo 1L machine on another.

Downloading music from YouTube will get you MP3s, but they will have gone through the YT compression algorithms.

Use Deemix instead. Downloads MP3s straight from the Deezer servers with all metadata and album art.

It depends on the version, but yes, it does. It’s especially a problem on prebuilt machines and laptops. It is incredibly annoying to work with in a corporate environment. Our helpdesk tech comes to me with issues related to this probably three times a week. I gave up with work arounds and we just have a throwaway Microsoft account now.