Regarding the issue of alternative/ different universes. Actually, it is easy to explain- it is the butterfly effect, but on a galactic scale.
It starts with the U.S.S. Kelvin. A ship that is out patrolling the galaxy. And on that ship was James T. Kirk's father- who ends up sacrificing his life, so that some may live. In the TOS timeline, Kirk's father was alive for part of Kirk's life, and was an influence on who he was to become. But in this version, he is killed- as well as the original captain.
Two men- who's time was cut short. Now, along the way, things COULD have happened- The Captain could have, in years to come, been transferred off the ship, and put in charge of something else- maybe the shipbuilding facilities on Mars. And during his time, maybe he could have been one to hold onto traditions and favored the ship designs of the past. Thus, a few dozen years later, we get the TOS ship that is so iconic in my memories from the 60's. A ship that was build in outer space, and therefore, was designed to be ONLY flown in outer space.
But, instead, the captain is killed- and with him, this idea of a traditional Enterprise.
Or- it could have been someone- an ensign, a crewmember, even a visiting designer- on the ship at the time of Nero's attack that witnessed what was happening. This individual, witness the raw, destructive power of a ship almost 300 years from the future, starts to design a new class of ship that is able to stand up to a threat of this nature. They use what limited information they have, to designed- or recommend changes- to the new types of ships being planned. Gone are the straight lines and smoothed edges of the Enterprise, and instead, there is a more fluid, natural feel to the ship- almost the opposite of the ugliness of Nero's ship. And this new type of ship is built ON THE PLANET EARTH!!! It is build in a place were gravity is going to play a factor in its design- where the construction crews are having to work with the constant presence of gravity in the design, as well as making it aerodynamic enough to fly through an atmosphere to get to outer space. (And maybe the ship is even designed for future atmospheric flights...).
So, see, it is possible to have the events from the movie- with regard to ship design- be in the same universe....
(Although I still think parallel timeline is the best way to think of it.... )
