Putting Uhura on the volcano mission and beaming her down to help Spock instead of a few security guards was silly. Putting her on those missions alongside qualified personnel would have been fine.
I think it would have taken too long to explain.
But I think Spock should have taken a security team down too and it would have been good to see Khan and Spock just leave the 'normal' Earth dudes in the dust as they ran across San Fran.
Can anyone remember whether the two security guys who went on the 'away mission' to Kronos lived. They weren't there when Kirk tried to punch out Khan