I've loved this show since I first heard the original cast album. Never saw it though.

Excuse my ignorance, but what do you mean by "music tracks"? Are you looking for recorded instrumentals of the score? Or are you looking for a recorded version of the show? If that's the case, I'd be happy to offer a CD of my vinyl Broadway Cast album.

Re: Rainbow - The obvious thing would be to shine a rainbow on a cyc or a scrim. Another possibility would be to shine the spectrum of lights onto the stage and actors bathing the stage left to right in violet, blue, green, yellow, orange, and red light as if the rainbow were shining directly onto the people, and the actors could be facing out towards the audience "marveling" at the sight. I think, at least, that's what I'll try if I ever get to direct this wonderful show.