RE: downhill shooting
First off a arrow flight is not flat, it must orginate at level with the ground and end on the ground. Causing the same curve that any object thrown or fired...physics class grade 9. Now it depends on the distance, etc to answer the question, but yes would be the answer based on the above logic. However the curve that the flight path of the object takes to the target will indicate what and if any adjustments is required. I generally aim at my intended target and fire...with no adjustment...kill zone is pie plate size so an inch won't make the difference if you have good placement. If you have deer jumping strings in your area, aim low like heart and then if they jump you got both lungs, if they don't you got heart.