That correspondence makes me lean toward believing that the prophecies have a real predictive value, independent of the Cylons' manipulating events to correspond with them.

Good point.

As for the Arrow of Apollo, I still suspect the clue to Earth's location will turn out to be a metaphorical arrow rather than a literal one. I thought it was going to have something to do with Lee, but now I'm wondering if it has something to do with Kobol's sun. Those ruins do bear a vague resemblance to Stonehenge; maybe there's an alignment coming up?

Could be both. My guess is: Starbuck comes back with the literal arrow. Roslin somehow, and I think via Lee, convinces them to let her go down to Kobol and try and open the Tomb of Athena with it. This works, but the result at first doesn't seem to provide any clues about Earth... instead, it provides them with some information of just what caused the theological split, the "war between the gods" referred to in a deleted scene - after all, it is the TOMB of Athena - which resulted in the current Cylonic monotheism versus human polytheism situation. Then, when they've given up the hope to find something about Earth, the metaphorical clue will kick in, either via allignement or because of something Lee did.