Water temp seems functional.. but doenst it serve the same function as Oil temp? if you oil temp is high and your water temp is okay, wouldnt you know to let the car cool down anyway? or am I mistaken?

What does a fuel pressure gauge do (dont say display fuel press) ? / how is it used/ what for? - does pressure increase / decrease based on an internal function of the car - Ie. running of it gas, yellow light on: the pressure gets lower gradually untill you are stranded...

please educate me, I have searched but cannot find a straight answer.

for example, boost gauge: used to vefiry that you are boosting the right amount, should your car feel slow then maybe if your boost gauge shows 2psi then ur turbo is leaking.. ect.

 

If your oil temp is too hot, you need to slow down. If your coolant temp is too hot, you need to slow down. The water can be too hot but not the oil and vice versa.

Fuel pressure can be useful if you're at the limit of the fuel pump. The pump may not maintain the proper pressure and cause you to go lean, resulting in a blown motor.