Shatner made a good captain, quite appropriate for the first series. In fact, he and Spock were what really made that show work. The actor that was truly odd, in my opinion, was De Forest Kelly as Doctor McCoy...but he did provide comic relief in his many tiffs with Spock, so the triumvirate of Kirk/Spock/McCoy worked rather well in spite of the fact that McCoy was so odd and hyper-reactive to various things (like cold logic).

Yes, Star Trek gave some lip service to traditional religion in a very generalized sense, but it was non-denominational religion that appeared to encompass the many rich cultural traditions of Earth's past cultures and meld them harmoniously with some new cultural traditions from non-Earthian members of the Federation. I call that a very progressive attitude to religion, and one that would be wise to practice in any reasonably enlightened society. Again, Star Trek was depicting a society far more egalitarian and democratic than our own, far more just, far more reasonable. These are things I liked about the show.

GUEST - Ah, the legendary kidney stone episode! Well, that one was never released. A copy of it is rumored to still be resting in some vault in Hollywood. I bet it would fetch at least a million on Ebay if you could ever get it in your hot little hands. :-D