I don't like it when character development is sacrificed for the plot or for special effects.
Then you're probably gonna love STID, because it doesn't do that.
I watched Iron Man 3 today. I liked how they depicted the character development arc of Tony Stark and Pepper Potts.
I thought STID is a lot more character-centric than IM3. I love RDJ, and this series is a tour de force for him, but sometimes the quirky comedy overpowers the drama.
I do have a question, which I am crediting to my mother - Supposedly Khan had this blood that could revive life. Bones revives a tribble with this blood, then revives Kirk with Tribble/Khan blood. If Khan had this blood, couldn't have he saved his wife from dying? Perhaps keep her alive, as Mr. Freeze did with his wife until he could find a cure? And, if Khan always had this blood, then how far back does this timeline diverge from the one that we saw in Classic Trek?
As for Q1, the most accurate answer is because this isn't RL, it's a movie. But an intra-universe answer may be that he didn't have the right equipment or medical knowledge.
Q2. Timeline only diverges at the point Nero's ship appeared. Everything else is explained in those terms.