Rojo8

I have been running 91 octane straight gas in my Z06, no ethanol. My Z06 is a 2008 with under 10,000 miles on it. I have a few qiustions.
1. Is straight gas good or bad?
2. Will ethanol cause damage over the long run?
3. Is 91 octane enough or should I add octane booster?

Any advice is appreciated.

Unreal

Not good or bad for your car.
No ethanol will not cause damage, in fact it is very popular to swap to e85 or e100 for more power, cooler running, more torque.
Car is fine on 91 unless you modded or tuned it to require higher octane.