You have to get a feel for the 'sweet spot', no too much or the engine stalls, not too little or you won't move the car.
Think of 2 pies, made of thick leather, facing each other. One of them is...
Brake fluid is what you use in a clutch.
There are different types of brake fluid, however, be sure to use the right one (DOT3, DOT4, etc.) Whichever is correct for your specific vehicle's brake...
Well at least nn a car, you need a clutch because the engine spins all the time and the car wheels don't. In order for a car to stop without killing the engine, the wheels need to be disconnected...