As for the differences in the look of the Abrams films vs. the rest of Trek, that's also easy to explain:
The crew of the Kelvin took detailed scans of the Narada and managed to upgrade its technology. That's why everything looks so much more advanced. (IMHO, the look of the actual Kelvin itself is entirely compatible with the TOS aesthetic..)
And there was another poster here (unfortunately I've forgotten exactly who) who suggested another reason: After the divergence, Admiral Marcus became the Starfleet c-in-c in the kelvin timeline, and pursued a much more militaristic and aggressive stance than Admiral Nogura did in prime.
Yeah, I've heard that before. I don't recall, was it in the novelization for Star Trek (2009) also? But it would make sense.
And I thought there were elements of the Kelvin that felt like they could fit in the years between Enterprise and the original series, though I'll admit maybe I'm projecting a bit. The only thing that felt out of place was the size of the ship, with 800+ people on board, is way more then ships at the time could carry..well, that and the window on the bridge (I know, a persistent complaint of mine).