Many tub/shower valves are designed to be used either as a tub only or as a tub-shower combo. You will note that the valves have inlets on the sides for the hot & cold water supply, and outlets top and bottom for directing water either to the tub or diverted to the shower head. By plugging the bottom outlet with the appropriate plug and either soldering or wrapping the threads with Teflon tape, the valve directs the water to the shower head.
You can if the base shape is compatible. Usually they are not, as few tub faucets are 'deck mount' and few lav faucets are wall mount. Also most tub faucets are 8" centres and all lav faucets are 4". - However if it fits and you like it there's no reason not to.
yes
Yes
A tub faucet acts as a shower and can be used to bath in the bath tub. It is a pressure valve which makes the flow of water through it constant and gives a nice shower.
The difference between a shower and a tub is the shower tends to enclosed with water that comes out of a shower head above while a tub has a faucet that pours into a large basin.
Defective divertor
It's the part of a tub control that makes the water go to either the faucet or the shower.
1- plugged shower head 2- defective diverter
The average is 16 inches, naturally there are some lower and some higher, according to requirements and design.
If the faucet contains the re-direction valve (closes off the water from the faucet and redirects the water to the shower head) you need to rotate the faucet counter clock wise to unscrew it from the plumbing and replace it with a new one. Take the old one to your local box store and they can match it up for you.
You have a leak between the diverter and showerhead or the arm for the showerhead is not sealed properly into the fitting in the wall
You need to do a leak test on the tub and shower. To ch'k the drain fill tub about 1/2 full without running the tub faucet next plug shower head and tub spout turn water on this will ch'k faucet Next run water on shower doors this is where the majority of leaks are found water running out and down the corner of the unit If tiled also ch'k tile grout.
It all depends what faucet is running if it is a kitchen or lavatory faucet it would be roughly 3 gallons if it was a tub and shower faucet it would roughly 15 gallons