RE: Elevated Shooting
I'm not so sure saying bending at the waist gets the whole meaning across. You want your shoulders in a "T" shape for good form. The top of the T is the line across your shoulders. You want that T pointing at your target, no matter where the target is, in relation to your elevation. You have to bend or lean from the waist to get the T (your shoulders) aligned with the target when the target is either below or above your elevation.
Just keep that in mind at all times and aim your T, your shoulders, while you are aiming your bow.
To get the feel of it, draw and aim level in front of you, HOLD THAT EXACT POSITION, then lean your body down to put your pin on the target.