Wow, this has gotten really puerile...
The difference here, deathmonkey, is that announcements for content that can be purchased is almost always made outside the game PRIOR to it's being available in game, not to mention it's something that generates revenue and is worth the time for HMX to draw up a press release, unlike a list of raw data that is and has been for a long time available in ga--... you know what? Forget it...
Your original question was:
"Is there a master list of all the songs available that also shows how many vocal parts each song has?"
The answer is:
That should settle this.