I will start with the second suggestion - well, it's because you can have more shows to play - and one might be graphics show on some screen, another one might be beam show with full size. And since Moncha can load only one show in workspace, this is for fast show load & play. I know, it's maybe problem when want to just play shows, but at the real event I believe it is good. So I'm not sure, if we should change this.
Well the music difference - yes, maybe it would be good to have some possibility to delay/forward show(and it would be best to be able to do that while playing the show). Good idea. Anyway, one warrning - it is recommended to use wav files, not the mp3s. Mp3 is not synchronized correctly(problem of windows codecs).