A sound idea, and the selection and explanation of the songs comprise a good, representative range of the genre. Like EchoMirage, though, I have a hard time figuring out how many the excerpted lyrics could possibly scan (except for a couple of the jocular lyrics, where strict scansion and meter aren't needful), and artistically they're comparatively pedestrian. I empathize with the effort; having been a lyricist and poet for decades, it's not always easy to churn out quality lyrics on demand, but the lack keeps the sub from top marks.
With the right kind of players, this can be an interesting plot hook.
Though, the mechanism of wish-granting could be subtler in some instances - at time it reads like a marketplace ("What does a leg get me?"); also, I can envision it sticking longer to one wishing person who has a great dream, helping him but consuming him in the end.
Plot hooks are good.
All in all, a good sub.