Stiffness is probably cos you have a hard spring. I have 550 front and 275 rears on mine for racing. My rear dampers are set soft and fronts in the middle for the bump/rebound setting. Turn the knob all the way towards the minus sign (left I think) then all the way to the plus sign and count the clicks. Then set them where you want them - I think my rears are five clicks from fully soft and my fronts are 10 clicks from fully soft. Too much in the bump/rebound and you'll find the car hops over bumps. If they are too stiff then you may want softer springs.

Height wise just adjust until you have a sensible ride height near standard - too low and the car won't handle well. Front slightly lower than rear.

Charlie