For the music and audio effects it might be time to use mp3's exclusively for this as the patents expired and use of mp3 has no apparent cost downsides for creators. This may help keep the file size smaller. Also I have noticed many applications supporting using compressed or deflated zip files to store the data and directly un-compresses the data files for use on the fly. This may be useful if you can easily integrate it with the html.
My bad on the decision tree comments. I was trying it from the first page and it was not obvious to me it did the choices....
thanks for your software! I look forward to using the desktop app version when its ready.