Im not snobbish about pastiche or cannon, some good, some not so good. I think though, Conan is strengthed by the contradiction, it reminds me of a real-life hero, where, years afterward, individuals are adding to the myth with their own stories, making the original character godlike or semi-divine. Strong myths are always built upon original truth, however. So, I can imagine Conan being a real hero, accomplishing almost imposible things in his lifetime, transcending his modest birthright, and going on to achieve astounding things. After his death, others tell tales of the mighty barbarian, so much that myth bacomes fact, as is the case with all of our famous historic personalities, from Julius Caesar to Elvis.
Its not whether he 'did this or that', its what we all imagine him to be capable of, like an aspect of the real hero myth. This is what gives reality and story potency.
I believe he could have done all those things and more besides.