...and the 'needs of the many' death scene works even better for me, in some ways, with Spock on the other side of the glass, saying good-bye to his newly-realized (rather than oldest and best) friend Kirk, and doing the "Kha-a-a-a-an!" scream of grief and promised vengeance. 

I agree, this was a surprise turn-around that really worked. Brilliant writing. I think some of us were dreading a re-do of “The Wrath of Khan,” because it might feel exploitative, but this twist, with Kirk taking the logical role and Spock taking the grief-stricken, revenge role, really worked for me. (Also, it starts me wondering what core themes they will revisit in future movies.)

While I loved that Spock went after Khan with murderous intent, by that point in the movie I was just plain tired of fist-fights, and it felt just a bit like more gratuitous violence instead of the dramatic role-reversal it was supposed to portray. I loved it when Uhura beamed down and just stood there blasting Khan – that really added to the theme you are describing in this blog about new dyads and triads forming that include Uhura. Plus, it gave her a warrior role, instead of the more passive role she often had to take in the original series. (She was a warrior in the "Mirror, Mirror" episode that she pretended to seduce alternate-Sulu, but the story treats it as play-acting to buy time for the men to do the real work.)