1. I never worked with MP3 files before so my question to start would be: Do I need to accomodate (add fields in mp3_mp3s table) these new info pairs.
For now I ignored them by expanding "switch -exact $info_key" with those parameters and ignore them when found.
I'd guess that the original code was just for "in house" use
for the developers and that they didn't try for an exhaustive