4. I will add a Radio support into a Pixie.
Logic is the next: have a new type of file:
Each file contains just an URL.
Pixie with show a list of files in folder so user could switch between them.
Since I prefer not to spend too much time to create the UI, I think it's a good idea to separate the player back end from the user interface.
My proposal however would be to use an already established protocol, which has many advantages.
(Player can be controlled from other PC, app on phone, ... Or KolibriOS if someone writes/ports MPD client)https://en.wikipedia.org/wiki/Music_Player_Daemon
(protocol is quite simple, see reference: https://www.musicpd.org/doc/html/protocol.html