Are there any resources to learn the any% JP route?

Just the videos!

For the speed/items: Press and hold A and B on Controller 1, then turn the game on. During gameplay, access the status screen via Start and press A on Controller 2 or the d-pad on controller 2. This enables very quick movement or gives you a bunch of items.

I'd recommend watching the 2nd fastest time and starting with that video as it does not skip refresh, which makes it way easier.