Ideally you wouldn't actually tune for a meth mix as that is when bad things can happen. You would use a mix that the STFT's could handle and you use the mix for cooling only, not actual octane.
That way, if you run out, which you will if you are doing actual lapping and not just Time Trial 2-3...
You are correct. Z723
https://www.blackhawkjapan.com/products/project-mu-z723-racing999-25?srsltid=AfmBOoo57MvX_y1h6Wo8fqzAeOXvgfkjy2HXT0_UZ3yZjXmlFgZkFTbY
Technically it shouldn't change alignment since all the suspension arms attach to the subframe. Shifting the axles from the diff shouldn't really do anything as they overall move independently of the hubs. (they flex in/out of hub/diff)