This problem lies with your pipe sizes. If the pipes size of your main line does not equal the supply for demand this will result in the current problem. For example, if your whole house is fed with half inch piping and you open two taps the volume of water has to be shared from the half inch pipe, thus causing a drop in pressure. Whereas if one installed three quarter inch main line "t-ing" off to half inch, because the three quarter inch will hold a higher volume of water when two taps are opened and the water shared, the drop in pressure will be hardly noticeable.
no
You have to undo the aerator at the end of the faucet and clean the screen or plastic water saver out. It will be plugged with sand or sediment.
you get a pressure gauge that screw onto laundry or garden faucet
A water pressure gauge. There is one mounted on every well pressure tank, and most well techs and some plumbers carry portable ones that can be screwed onto a garden faucet to read home pressure
It needs higher air pressure.
Possibly a pressure reducing valve installed after piping for first faucet, which would cause situation describing.
No, too high of water pressure causes problems.
The faucet is clogged
well if you have a plugged aerator or your water line is corroded then that is usually the reason a faucet has low pressure if its just one faucet.
no
No. It takes much more than water pressure to turn on the water faucet. At most, there is a leak if anything at all.
It is pushed by the water pressure in the system.
A Roman tub faucet does have good water pressure because it is made to do that. How good this is depends on how other brands perform in this area.
The water pump.
I would purchase a Watt water pressure guage from your local home improvement or hardware store and check your water pressure at your faucet. If water pressure is greater than 40-45psi your regulator needs to be turned down where the water comes into the house.
Unscrew the aerator from the end of the faucet where the water comes out and clean the screen. Sediment build up slows the flow.
You have to undo the aerator at the end of the faucet and clean the screen or plastic water saver out. It will be plugged with sand or sediment.