As for Jabba being on Tatooine. I don’t really have a problem with it. Luke was always going to go back to Tatooine. Anyone who says so flippantly "I’m never coming back to this place ever again: is doomed by irony.
True, but there’s nothing in Luke’s return to Tatooine in ROTJ that makes any kind of ironic connection other than “Oh, gee, he had to go back there for a minute, and then leave again.”. If he had been holed up there studying the force or whatever because he felt “centered” there or something, then that connection would work. As it stands, there’s no reason to have Jabba’s palace on Tatooine.