RE: arrow on draw
Just because your rest is behind the riser of your bow a little ways does not mean that it acts like an over draw.
Remember that you are shooting a drop away rest. So the arrow is resting on the riser when the bow is relaxed. As you draw the string the rest rises and should be in the fully up position about 3 inches before you reach full draw.
You MUST cut your arrows to a length that will allow the arrow to rise sufficiently BEFORE your broadhead gets to the front of your riser.
The extra inch that you are cutting off to get a shorter arrow is so little in terms of weight that you will never notice the difference in speed or trajectory. It's only about 7 - 10 grains depending on what arrow you shoot.
If you want your drop away rest to act like an over draw then you need to purchase one of the drow aways that you can lock in the upright position. Such as the QAD ultra rest or ripcord. With the rest locked in the up position you can cut your arrows as short as you want to.