Do note that some of those "jets" are meant for cleaning the toilet and not for hygiene. When buying one, make sure you are getting the right one. The difference is indeed in the intensity with which the jet of water is ejected from the device.
Ok. I think hygiene depends on municipal water pressure then, unless one uses a bidet with built-in compressor.
probably.
I used to wipe the first times I used my bidet, because I didn't trust it.