I have a 1.6L 1990 Miata. It is a manual (5 speed, of course). Defect of the car was a crankshaft wobble. Had a piece fashioned to stabilize it, but the pulley finally fell off - I got 250k miles out of it, so I can't complain.

At any rate, I would like to swap the engine, possibly to the 1.8L manual. What I would like to know is:
1. How much modding would be involved? ie, engine mounts, fire wall, wiring etc.
2. How much of an issue is going from 5 speed to 6, or will I have to replace both the tranny and ECU?
3. I would eventually like to turbo or supercharge it, so the 94-97 1.8L might be ideal since I understand the rods to be stronger and they can handle up to about 15 psi. And it has the benefit of being pre-OBDII. However, can this hook up to the 1st gen 5 speed tranny without much trouble? Or will this also require the tranny/ecu switch, even without going to the 6 speed engine?
4. If I was able to find the BPT engine, how would that swap go, since it wasn't applied in the US?
5. How would a BP-4W (Mazdaspeed stock turbo engine) swap go? Anyone done it? Or would it just be easier to turbo charge after the fact?

Sorry about the long list. Anyone can just answer any one part. I am grateful for ANY and ALL help.

Kind Regards,
Lisa