Head Six never "clearly" stated anything! She only became clearly an angel in what, the last episode? She very well could have been an implant or schizophrenia up until then...her motives certainly didn't seem clear. The cylons had no plan, just like the writers!
Starbucks destiny? Right, wasn't that said when the cylons had captured her as part of an eventually abandoned breeding plot line?
No...there is an episode earlier on in season 2 where Baltar gets his brain scanned. He finds out he doesn't have a chip in there. He also then realizes that Head Six seems to be telling him a lot about things that will happen in the future, and she had been surprisingly accurate with that in the past. He then deduces he's also not crazy, so he asks her what she is. She specifically states she is an angel of god.
I just said that Leoben talks to Starbuck about her destiny earlier on in season 1. It's the episode where she is sent to interrogate him on another ship. And it's not just lightly brought up...he talks about it quite a bit.
Like I said, you probably need to rewatch it. You'll be surprised at how religious the show is from the start, I think.
What the series lacked was a clear-cut antagonist. Dean Stockwell was great, as usual, but the character of John Cavil was insufficiently threatening and couldn't be taken seriously. Since the show focused so much on the religious aspect, the absence of a Satan figure left a gaping hole in the overall storyline. The Cylons had no plan because there was no Count Iblis pulling their strings.
Oh, and not only was breaking the fourth wall with a Dylan tune an idiotic idea, but that particular rendition of "All Along the Watchtower" was terrible.
I do agree that the show lacked a clear-cut antagonist once more of the Cylons started siding with the humans. Cavil being the "main" antagonist was kinda lame, but I don't always feel like there needs to be a main, strong antagonist type idea or character in stories like these.
BSG's rendition of "All Along the Watchtower" is great, even if it wasn't part of the show! Not sure what you're talking about.