FWIW (re the historical "accuracy") the creators have stated in interviews and commentary tracks that they've very deliberately creating a fairy tale universe that borrows liberally from anywhere within the range of potential Arthurian legend settings (which I think they've pegged as anywhere from 6th to 14th centuries). So... yeah they're all over the place, but it is a deliberate pastiche and not just a series of fuck ups.

And yeah, Arthur and Merlin aren't best served by still shots, but they get WAY hotter both in action, and as the cinematographers seem to learn how best to light them.