Starships of the 2230's :
1. Relied mostly on beam weaponry
Where do we get this? The Kelvin did; doesn't mean other ships would have.
2. Had a cruising speed of warp 4, max warp 8.
Again, how so? We didn't see the Kelvin at warp. A quarter of a century later, we saw a fancy new starship do warp 4 when damaged on a maiden voyage, which doesn't give us any information on the warp performance of non-new, non-damaged ships on regular operations.
3. Were in the normal size range for starships.
That goes by definition, of course: even if the Kelvin were two centimeters tall, or perhaps two kilometers long, she'd define "normal size range" for that era.
Externally, the Kelvin was obviously shaped to be a bit less than 300 meters long - in contrast to, say, the TOS Enterprise whose surface detail wasn't completely obvious and whose dimensions thus were easily fudged during production, or the Voyager whose size-establishing surface detail was explicit and whose dimensions were also quite explicit (and never mind that this contradicted some interior views rather badly). Internally, the Kelvin was shot at a size that might be on the upper edge of what we consider "normal", but still not exceptional in comparison with some TNG era designs or earlier plausible-looking fan creations (say, the aforementioned Proxima battleship).
Timo Saloniemi