No, the B20A or B21A motors will not fit into ANY other car than the 88-91 Prelude it was intended for. This is because the engine block was designed to sit at an 18-degree rearward slant in order to clear the low hood-line of the car. So these motors will not work in anything but a 3rd generation Prelude.
If you intend to make it work and swap a B20A or B21A motor into a 4th generation Honda Civic then by all means have fun, but it will be neither easy nor cheap to do so because a lot of custom fabrication will be involved. It would be a waste of time and money.
No, the Honda Civic springs is not compatible with any generation of the Honda Prelude.
No. The Prelude has a B20A5 motor. The civic will have a D-series tranny. They will not interchange (B and D series parts do not interchange).
The 97 Honda Prelude motor (h22a) will fit into a 2000 civic with custom mounts (available to purchase online), however you will need the h22a transmission, shift-linkage, axles, and ecu (full swap). The h22a motor will not work with the stock d-series transmission.
no
Unless you fabricate them in some way to fit, it won't fit any generation of Honda Prelude.
yes
yes
No, different bolt pattern.
NO, they have two completely different motors.
yes, the motors are interchangeable.
No.
You could, but because the '94 Prelude is heavier than the '89 Prelude, it doesn't make sense to swap in a smaller powered motor.