I know that the music of the EWP changed sometime after The Little Mermaid was released...song became more TLM-based, instead of a mixture of classical and lesser-known Disney songs. I know that as far back as 1991, it was still the "old" songs. Last I saw the attraction though (probably around last year), it was still LTM music.
If the music is commercially available anymore, I've not seen it. I have ample homemade audiotapes and videotapes of the show somewhere in our storage unit, but they're not apt to see the light of day for another 6 months or so.