Contractors need to seek out workers who have some idea about the kinds of work they will be doing, who are trainable, have good communications skills so they can talk to customers and contractors, and be able to write legible reports that wil be acceptable if they are ever used as evidence in a court case.
Logic states if you have the same amount of air available to push the water out, you will be able to deliver the same amount of water between the pump cycles regardless whether the tank has a diaphragm separating the air from the water.
Some of the more dangerous conditions that can be encountered during drilling include underground fuel tanks, high pressure gas lines, high voltage electrical lines, and lost circulation zones which can catastrophically collapse and consume a whole drill rig (and crew) in minutes.