<<Why do a good number of people say you need a tripod with D800 to get maximum results? Yet the same is not said about the D7000?>>
Craig, with the very greatest respect if you had gone through the trials and tribulations I went through with my D7000 you would know that the same was said about the D7000.
I was running out of ideas of how to cure my problems in achieving sharp images, or even many in focus. My first copy was ascertained as faulty, the second was better, but much of what you are saying is a carbon copy of my frustrations.
I think that one can get so immersed in trying to rectify a problem as I did, so one cannot see the wood for the trees. You are showing all the signs that I was and the D800 now may well be a lost cause, as my D7000 was to me at the time. In fairness my D7000 takes great pictures now, same camera, same photographer and taking all that into account it still affected my view of the camera. Perhaps I really don't want to admit that much of the problem was me, That's ok as we are all human
If you keep the D800, you will master it and please let us know when you do as that will help others.