Look into what it would take to add the ability for python to edit the metadata of (.mp4, .avi, .mkv, .m4v, etc.) without having to rely on the operating system itself. Meaning, I don't really want to use ffmpeg because it doesn't work on every Linux distribution.
If subtitle files are present within the same sub directory as a media, bring the info into the queue screen, provide the same options to edit the file name and such, and then load the modified subtitle file into the same final directory.