The trigger voltage is NOT based on the voltage of the batteries. There must be a capacitor somewhere that discharges.
The pin layout is based on what features a flash provides, usually with a specific brand of camera. For example I have a Minolta flash that, with a Minolta camera, provides through-the-lens metering and automatically zooms the flash head when I zoom the camera lens. The extra pins are used to control those features. With my FZ10 it only works as a (very poor) manual flash because only the center pin is used.