Need some clarity on set up form

[MX_KEVIN]

For the clutch, it spins counter clockwise looking from the front sothe shoes can "lead" the pins or "trail"the pins. With the stock SW clutch, trailing is the only option.
Your right on the pistons. Not sure if SW has diffrent options for pistons, but some poeple modify by drilling or tapering the holes.
Ground clearance is the same as ride height. Most measure by looking at driveshafts. If their paralell to the ground, thats a good starting point.
Roll center?I need help on that one also.`It might be the position of the upper link on the rear. Top or bottem holes.
this link may answer all the questions
http://www.chitownrc.com/showthread.php?t=1677