I learned something really important with KiCad today.  Whatever you do, if the assign components dialog asks you if you want to annotate and renumber your components, do NOT do it if you've already routed the board.  I thought it would renumber my components in both the schematic and layout with nice top to bottom numbers.  Instead, I think it renumbered in the schematic only.  So next time I updated my PCB layout from the schematic, all hell broke lose and components swapped locations and orientations all over the board.  I'd saved while still in the schematic view, so there was no undo.  It took about 2 hours to re-place around 100 components using the detached traces I'd been routing all day.  Luckily the rough routing was done, and the highlight net tool cross-referenced with the schematic was very helpful.

On the bright side, I did get all of the functionality I wanted packed into the schematic and roughly routed.  I managed to use all but ONE outside row pins on the Teensy 3.6.  Tonight I'll test the pin assignments with my breadboard setup.