Kirk would have been a teenager during the Kodos time on Tarsus IV, if memory serves me. I don't see a reason for it to be hashed out here. And honestly, there's not a lot we need to see, except maybe where he spent time as an XO, since he was probably one of, if not the youngest, captains in the fleet. And to get the Enterprise as his command... clearly he did some great stuff in his career, stuff we have not seen. (Or perhaps "A Quality of Mercy" is essentially how it happened.)
As much as I like M'Benga and feel for what he's gone through, we should eventually get Dr. Boyce for the simple fact he seemed to have a close friendship with Pike in the original pilot. I'd like to see that explored, because that scene in his quarters when Boyce says bartenders and doctors see the exact same types of people, "the living... and the dying", was a great scene.
Regarding Chapel and Uhura, we really didn't know much at all about them except for a few vague references and pieced together information. I find it a nice tribute that they are both here, since Majel Barrett died years ago and Nichelle Nichols recently.
Plus, both actresses have been doing great in their respective roles.
