I'm sorry, but I haven't asked my emploeyer if I could program here at work... so I'll just post instead!
About MP3 playlists, there are three possibilities:
1) You use the Favorites already inbuilt ability to open an external program with an external file to open a different playlist with your current mp3 player, this is already enabled.
2) I make a "playlist" option for each favorite and you define your preferred player once in the settings, this is the way I'm likely to go as it's easy and quick.
3) I make my own built in player, it seems to be free(?)
http://delphi.about.com/library/weekly/aa112800a.htm
BTW, I use delphi, still many bits to piece in, gotta make fail safes and error handling, and code that avoids errors.