Apologies I'm not quite understanding the music point still.
The slight movement lag is unfortunately a bug in the plugins I use and it not handling one of the mechanics I use in the game very well. It's a bit technical to go into, but generally it's more me choosing that its an acceptable trade-off after I scaled back some of my original plans. I'd have to choose to revamp that system considerably. Maybe one day, but for now I have no plans on that.
Noted on the walkthrough. I could probably add a thing there. I think I've just assumed it to be "obvious" in my head, but that's my bias as the creator talking.