Hm, so you would suggest having playlist items numbered. But then send for example program change 2 would bring a different songs depending on the playlist. I don't think that would be very practical. I think you want to define a specific number for a song and whenever you send that pc command, the same song will be loaded. I guess that makes more sense.
And yes, multitrack playback is already on my todo list but there are very few requests for this feature, so I have not yet scheduled it for a specific version.