If you know how much K you have applied and what the tissue concentration is then you can adjust up or down as needed the following year. Not that I am aware of. In all cases potassium sulfate is preferred over potassium chloride. Frequent light applications of K would allow it to be more available than 1-2 heavy applications. However, see the answer in D above.
Research shows no effect of timing on yield.
Cranberries are sensitive to chloride, so the sulfate form is preferred. There isn t research to support this that I know of, but grower experience does. Always choose the sulfate form. There are no data to support early application of potassium causing better fruit set or yield. Mini-clinics are free, informal educational sessions hosted by your fellow growers.