Things that should have been obvious, but I've recently discovered

[antimony]

So ...anyway... am I wrong in thinking that the depth and reach of the bars has nearly nothing to do with the ability to brake from the hooks, and that it has much more to do with the *shape* of the bars, particularly how sharp or how gradual the transition, as well as with where the levers are positioned on that transition?

(and another point of terminology that I don't know - what does one call the part of the bars between the tops and the hoods, the part that's basically nonexistent on short reach bars but can be very roomy longer and on old-fashioned bars?)

I agree with your first part completely, and as to the second, I've heard them called "ramps". (Love my old-fashioned bars with big roomy ones -- Velo Orange Grand Cru Course.) I do call all of the lower part of the bar "the drops", though.