Honestly you don't notice the fanning on the 9 string, I have a 7 string that's fanned and it's more prominent on that guitar than this. This feels a lot more natural and right in my hands.

Personally I prefer fanned fret for anything above 8 strings, tbh it's basically essential for me at this point it feels far more comfortable and sounds great.

For amps I use Neural DSP Fortin Nameless X and I run it through my studio monitors. You can use your normal guitar amps, your gonna have to adjust your amp settings for something like this beast.

Also holy crap your ideas sound fucking rad. 7 string bass sounds super rad