Follow the manual. I've found that it DOES matter WHERE you shim the clutch from and I like to shim as much as possible from behind the flywheel keeping the shims above the thrust bearing to a minimum. On a nova you don't need much behind the flywheel but on an os I've found you need a good 0.6-0.9 behind the flywheel before you get close to the ideal 0.6mm clutch gap. By shiming behind the flywheel you should get a snappier clutch than all above the thrust bearing as the shims can act like a spring if they are not absolutely flat. The shims can also warp with heat too. The above is based on the serpent reverse centax but the theory works for all centax style clutches.
The end float is shimed between the end of the clutch nut and the end bell bearing. Just shim until the end bell clears the clutch shoe. No need to measure it.