Your first section on media queries is the reason I continue to use Foundation over Bootstrap. Bootstrap is still stuck in Pixel-Land and that is becoming more and more cumbersome in multi-device layouts, mainly for typographical reasons. Once you switch your media queries from pixel to em based, you have a world of difference of end-user experience, across any screen size.
We did not learn this on our own, but through the wonderful article by Lyza Gardner, here: http://blog.cloudfour.com/the-ems-have-it-proportional-media-queries-ftw/
We’re waiting for the day that Bootstrap finally gets rid of all their pixel measurements, because until then, whenever we have to deal with it, we’re continuing to edit/override in order to truly fluid. Note: percentages do not render as well as ems/rems.
Finally, with 504 Compliance hitting my team’s radar more and more, again, we have to go strongly in the direction of proportion, as opposed to the more rigid measurement of pixels.