Upgrading clutch
#2
Stick with oem. The only reason to upgrade a clutch is if you are pushing a lot more power (turbo, etc.). It's one of the few parts that you should only upgrade if you really need it. There are zero benefits of an "upgraded" clutch on an engine that is stock or just had bolt ons.
#4
Yea, plus the oem clutch on these is quite good. It's very light and easy to modulate. It'll also last a long while if you're good to it. I had to upgrade mine to a higher torque unit at 115k since I went turbo, but the original disk still looked great at that mileage.