I have noticed that in sound edit for each part there is a switch for Original Tuning. Most of the time it is off. I also saw this under the key menu. How does this work

Question #2. How do edit an sound to be a tremelo or vibrato?

well tremolo is variation in volume and vibrato is variation in frequency so you can do both of these with the low frequency oscillator.

sound edit / LFO

page 1 is the vibrato and page 2 is the tremolo.

you can have different amounts, delays, waveshapes, keysyncs, phase, touch etc for different samples in the final sound. The programming is pretty advanced since you have 12 LFOs you can program to affect different samples in different ways.

If you press OVERVIEW you can see how it is all mapped out in the screen.

Try a tiny amount of effect in the actual sound, and some (slightly different settings) more triggered by touch, and some (slightly different settings) more in the wheel, and you have that really complex effect that never sounds like a constant sine wave... You can program any 2 of the 12 LFOs into the modulation wheel.

I forgot about the original tuning. I think this is difficult to hear because very subtle.
You can change the tuning for individual notes for individual parts and set it to all those various arabic and kirnberger scales that you need a text book to figure out what is going on.

As I see it all the natural instruments have their own tuning curve, a real piano is not tuned equal temperament but higher at the top and lower at the bottom. So if you do your own scaling you can implement it exactly as the screen or keep this natural tuning curve on top.