Droop is the down travel your suspension will have beyond ride height. When you lift the car from ride height it is the total throw until the wheels come off the ground.
Less droop will help in high bite situations. More droop will increase traction and will help on hard landing areas.
You should have a little less droop in the front than in the rear. Do not dial it all the way out.
If you need a little more steering going into (slowing down into) a turn then add a little rear droop. It will help the car transfer to the nose where you need the traction.
If you have too much droop you can high center and traction roll. Too little and you will bounce all over the place.
Hope this helps some.
TEX