As for why Ben would say that Vader killed Anakin in ANH, we might think it's to cover up the fact that he killed him.
Thats actually pretty plausible considering the look/pause Guiness gives when almost 'winding-up' to tell about Vader. Also, ADM said that he would try and tackle this as well, so hopefully between everyone working on this concept, something good will have to come out of it.