Well, sorta figured out. I got a friend to explain to me two different ways controllers can work, requiring the float switch to go in two different places. But it works, which is the most important thing for now.
The holding tank is because the well only yields 4 or 5 gal/minute.
I'm in western OR and yes we get a week or so of freezing weather once or twice each winter. But insulation and a heat tape or even just a light bulb is plenty to prevent freezing.