Would be the shift lock button.
Usually you cant pull the car out of park unless the ignition is on and your foot is on the brake
The red button allows you to bypass that, need to hold it down and move the shift lever
No gain by just switching fuel
More boost and timing will be needed to make more power
You will often find it will be a little laggier with E85 or it might go the otherway, each engine/tuner seems to report different results
Go E85 and wind 28psi into the thing and you will love it
Just put a standard clutch in if the car is standard, and going by the fact you are posting in the NA section I'm assuming the car is pretty basic
therefore as above, standard NA clutch or if you want a little more bite a standard turbo clucth
Ive had a couple of rims crack over the years, checking the wheels is part of the car wash routine and also if Im standing near the car I'll do a quick walk around