I think autocoarsen was an optimized blade angle of 55 1/2 degrees, which provided the best single engine climb performance. A pump was used in cruise flight to feather the blades completely. At least one of the available props for the 340B was designed to fail to the autocoarsen position should prop oil pressure be lost.

Think of CTOT as a very simple autothrottle, used only for takeoff. You preselect a desired takeoff torque setting, and watch the magic happen. The fun part is when you turn CTOT off during the climb, and the torque drops off to what the power levers are actually commanding (may be a torque increase, but often a torque decrease). You never know what you're gonna get!