What Did Uncle Owen Know???

What did Uncle Owen know about the fate of Anakin?

We know that he knew Anakin was a Jedi, and was fighting in the Clone Wars. Then one day, after the war was over and the Empire had been created, and the Jedi were outlawed and killed, another Jedi whom he never met before shows up with a baby that he said was Anakin's son. We know he tells Luke that Anakin was a navigator on a spice freighter. Obi-Wan tells Luke that his Uncle didn't think Anakin should have gone and gotten involved, and was afraid Luke would follow Obi-Wan like his father did. The dinner conversation between Beru and Owen confirms this.

But what did Owen actually know, and what did he think was true? Did he know that Anakin was now Vader? Or did he think Anakin had been killed with the rest of the Jedi during Order 66. And did he even know that Vader existed, or that Luke was a twin? Also I'm guessing he assumed Padme was the mother, and she had died during child birth. But was he told that he could never tell anybody that it was her child, and the rest of the galaxy needs to believe that she never gave birth to the child she was pregnant with.