OCRC & WCRC

What does running 2mm or 3mm shims under the rear camber links do exactly. I know running more inboard gives it a bit more rear bite, but what happens when both are raised up. Does this lower the roll center?

More spacers will generally make the car drive more "square" and should increase forward drive.

For more rear traction will going to a higher degree toe block help or is it the opposite? Also what does shortening the wheelbase affect?

Toe - More toe generally equals more turn in, less center off steering and more forward tracion

WB - Shorter will put more weight over the rear axles, and increase forward bite while generally reducing side bite entering.