They are right there on the top of the engine.
yes
does a 1990 honda prelude 2.0 s.i have a pilot bearing
http://www.modifiedlife.com/1990-honda-prelude-car-radio-stereo-wiring-diagram/
No, the third and fourth generation are a different Chassis.
no
6.5"
NO, they have two completely different motors.
show me picture of where the water pump is located on 1991 Honda prelude si
8 spark plugs
the fuel rail
It's hard to say, as the question didn't specify what kind of solenoid are you attempting to fit, and the 1990 Prelude had a mid-cycle refresh which included an improved motor.