You've got it.
Fill the sump? Don't bother- just have enough water to cover the motors, as they use that for cooling.
You can use a hooked stick to manually raise the floats.
The Dayton panel is made by SJE-Rhombus. The third float will both sound the alarm and start the second pump. The panel has an alarm silence switch that will quiet the horn, but the light will continue to flash.
