The cycling switch unscrews from the accumulator. No need to drain the system, there is a schrader valve in the fitting on the accumulator.
Yet another colossal example of worthless literature. All Data, Chilton, Mitchell and Haynes manuals: I suppose each one is good for something, but how do you know what information is correct? If you want correct, complete information and specs, get the factory shop manual for the vehicle you're working on.
As charge level decreases, compressor ON time also decreases. Not sure if 2.3X ambient would work with R134a in a CCOT system, probably not. Both high and low side pressures are constantly changing.