As for Anakin's parentage, I always imagined that Anakin and Owens' parents had died in some accident and they were left to fend for themselves. They bought a moisture farm and Anakin bought a ship and got into the spice trade. "He was a navigator on a spice freighter." being not a total lie, just not the whole truth. I always figured Vader just wouldn't go back to Tatooine because it's a place of pain for him, a reminder of who he was before he became Vader, which is what he wants to forget.