The library is where I got all of mine! I had to get a few through interlibrary loan, but it was worth the wait.

They do sing the songs, and most of them are extremely catchy! Most of them have background music for the songs (the only ones I remember not having it are Taggerung and Martin the Warrior, but I could be wrong on that). The singing quality varies, of course, because it's usually just the voice actors singing the songs and some of them are a touch off-key, but it added a lot of character as far as I was concerned.