On the first point, I'd say they're all subcategories of comics. So no, you can't judge two subcategories by the same standards. Manwha has different cultural and artistic (and professional) standards than manga, etc. As for using the creator, I don't know much about that. But I'd hate to see one standard for all those comics, since even though they could all be apples (so it's not like comparing apples to oranges), a Macintosh still isn't a Red Delicious.
...Ok, the late night has caught up with me and my analogies.
You seem to have put a lot of thought into your arguments and you pretty well-informed. I guess I'd have to know more about the issue to really say much else, and in the midterm season, that's unlikely to happen. ;)