Jellyfin is a fork of Emby due to some drama I can't quite remember. Last I used Emby a few years ago, both looked and operated basically the same as each other.

Jellyfin has made improvements since. I can't speak for Emby since I switched to Jellyfin.

They are not making a Linux build, but they are making sure the Windows build plays nice with Proton. At least that's how I read that.

As many have already said, the math needed will depend on what type of work you're looking to do. Writing business software, for example, rarely requires more than basic arithmetic.

However, I think that the logical thinking skills that are needed for math are also necessary to be a good software engineer.