Sam's photo shows the correct way to adjust the release fingers. The PTO adjusting screws should be set to 090" as a nominal figure. If the main plate has significant wear and is refitted the release fingers will protrude further. The further out they protrude the smaller will be the lift on the PTO pressure plate. Assuming that the fingers are well in and you have approximately the depth of the finger for the screws that is about correct. It is vital that the head setting above the plate hub is the same for the three even if the actual height is not to the gauge. Any difference can be adjusted at the release bearing.
As to the plates in the right way? Yes, some can be fitted incorrectly but most will only fit one way.
DavidP, South Wales