One major lesson learned here that eclipses everything else:
1) I can re-order my factory's build queue. Do not do this for the first group in the queue, it will destroy the unit that is under construction. Instead, right-click to subtract all but the last unit, then re-add them to the end of the queue, then re-order everything but the one unit under construction.

And comparatively minor lessons:
2) During the window from 2:00 to 3:00 I should position my commander near support in anticipation of a Revenant unless I've already scouted/identified all enemy factories. It doesn't matter how much my assigned tasks are stretching my resources, or whether I think my opponents know where my commander is, for that one minute of the game I need a contingency plan to protect my commander or else it shouldn't be active on that part of the map. Delaying a few mexes by a minute each is worth avoiding the potential com loss, particularly if there are other slightly useful tasks like map feature reclaim in base.
3) Revenant artillery is still slightly functional, but much worse than direct action. Save it for after the opponents have dense enough defenses to prevent said direct action.