@plainsane, great summary & explanation of advanced zone settings 
Just a few notes to help clarify:
Soil type determines the Available Water (see below) and infiltration rate for each zone. The infiltration rate of the soil, nozzle application rate (precip rate), and slope are the inputs used for Smart Cycle. To learn more about Smart Cycle, please see this support article.
Exposure affects the microclimate of your zone. Shade settings will decrease your Landscape ET calculations.
Efficiency is also known as distribution uniformity. To calculate it, you’ll need to perform a catch cup test for each zone.
Available water is dependent on the soil type selected. To learn more about how it’s calculated and it’s importance in irrigation scheduling, here’s a good quick read on the subject; or for the water & lawn nerds, here’s a detailed article that gets into the science. Please note, changing this value can have a huge impact on your watering schedule. Only edit it if you’ve done your research.