1990 Prelude Si ALB - Last Time

Me again, as you probably guessed...
OK, I saw where it was recommended that I replace my B21A1 engine with a B20B from Nippon Motors. My questions are:
1. Would this engine replace my B21A1 without having to replace the ECU, transmission, wiring harnesses, etc.?
2. Would a B20A5 work better since it is the same block-cast as the B21A1, and was used in the 2.0Si Preludes thru 1991?
3. Wikipedia says the B20B engine only produces 126hp, while the B20A5 produces 135hp. (Granted, neither of them produce the 140hp like my current engine, but I could deal with losing only 5hp) Are those numbers correct?
4. Nippon has B20B as a 97-99 CR-V engine at the top, and then has it at the bottom as a "performance engine". Does anyone know what the difference is, if any, between the two? (The price is the same)
Thanks again to all of the great Honda minds out there! :-)
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