Hi
A manometer is a pressure gauge, and it is connected in the fuel line, the delivery or return valves are the ones on top of the pump, they increase the pressure clockwise, you can only turn then 15* or something like that, I have and idea about how the whole deal works inside the pump with the governors, the centrifugal thing and the other parts but I will need to get a book or a Bosch manual if I want to get very precise about it.

The WVO temperature is a very long discussion for many people, I think since Lord Kelvin times is very clear how it works, the viscosity of the oil changes with temperature a lot, lard is dangerous in any way or temperature for the engine, but just warming the oil doesn't have any effect in the start with the cold engine, now it is running with a mix of 70% oil and 30% dynodiesel, and since the tune up just works perfect with no smoke at all, even wen starts.
I think that there is a lot of wrong concepts and mystification about the WVO, the centrifuge filter seems to be very good about taking the water, lard, and many other particles from the oil, it has some troubles with lighter stuff, in the other hand is very fast and pretty much trouble free.