I recently watched this talk by Scott Johnston posted on Facebook here:
[Direct link not working. Try this one after removing the spaces:
https :// http://www.facebook.com/ uphillathlete/ videos/ 1207164636050638/
It addresses several of your questions. Unfortunately, I can’t remember exactly where in the talk they occur, but you might skip through until you see graphs showing lactate curves and also X-crossing blue and red curves of fat vs. carb utilization in the latter half.
Nice VO2max! I’m jealous.