EUREKA!!!
[I think]
I figured out how to keep my stone windmill in semi-continuous production. I had a batch processing and decided to see what would happen if I clicked on "Start Production" while the mill was already working. Voila! 10 units of wheat went into "Pending" and one XP popped out! So I added a few more. I now have 35 units pending, one in production, and one produced (in addition to what I have already produced). Now to just figure out how much wheat I can add to pending before the mill either grinds to a halt or eats my wheat without making flour!
