That doesn't explain the rest of the laundry list.
Well pardon me. I answered the one I thought I could do well.
I see no problem with there being large UFP ships before the NCC-1701. The Kelvin was probably transporting colonists to and fro, seeing how Winona should have been heading home for an Iowa birth before it got waylaid by the lightning storm.
Bev Crusher's medical ship in "All Good Things..." was based on a very early pre-TOS ship design and it seemed pretty big.
The assumption during TOS was that the Constitution was the largest class of starship Earth had ever built, as per "The Making of Star Trek" (and yes, the term "Constitution class" dates back to the time of the series; it showed up on a graphic Scotty was studying in "The Trouble With Tribbles" and was incorporated into the 1968 version of the Concordance).
Previous slip-ups in continuity have generally been around the margins, minor details that don't effect the story and can be worked around. This movie blows big honking holes in the continuity that you can't just squint and pretend aren't there. And that's
before Nero blows up the Kelvin.
So, sorry, but it's one big alternate timeline, beginning to end, Nimoy's Spock included.