Best to look at the mfg data. They are built in a plethora of configurations and cover a wide range of pressures. Some use a 0-10VDC signal, some use a 0-20mA signal and some have proprietary digital signals.
How they work? Early designs used something akin to a variable capacitor. One fixed plate (the case) and one moving plate (the diaphragm) I believe that the latest tech is piezo-electric strain gauges. Some crystals produce electricity when squeezed. Think the "snap" lighter on your BBQ grill.