RE: SHOOTING HIGH OR LOW FROM TREESTAND?
This seems to a tricky question for the simple reason that your going to some diffrent answers and opinions but yes when shooting from a treestand you should bend at the waste.
As for aiming low or high thats where the trick comes in , many bow hunters think you should aim low because the deer might ( jump or duck ) the string as you release.
While other hunters say aim high to allow for the angle they are shooting but the best advice I would give you would be to shoot as you had practiced.
Now I know shooting at a target from a treestand is diffrent than shooting at a live deer but if you had been praticing your angles , you shouldn't really have any problems hitting at what your aiming at.