I would get the 4n1, should be great for clean up work. As far as the box blade, I wouldn't get the 72", just to big. I would try to find the heaviest 66" unit that you can, you will be happy with that size. And I would get a 60" before I got a 72" unit, but a 66" would be ideal. Are you getting 1 or 2 rear remotes? If you are going to be doing much grading, it sure is nice to have both the Top & Tilt cylinders for the 3pt hitch.
Sorry that I can't help out with the back hoe question. Good luck with your search and decision.
Sorry that I can't help out with the back hoe question. Good luck with your search and decision.