As regards the sountrack...

The liner notes say that the reason music from the movie wasn't used is that the actors & singers learned only the parts that appeared in the film - i.e., no full-length songs.

However, there has since been released a Songcatcher II, which has recordings of traditional singers singing songs in the traditional way. If you don't like the modern stuff on the first one (and I do, very much, by the way), you might like what's on the second.

My biggest beef with the first recording is that it doesn't include any historical information about the songs.