Engine Swap Questions

I have searched Google until my fingers went numb, but still can't find a definite answer to these questions:
What other engine(s) (besides the B20Ax and B21A1) will fit in a 3G
(88-91) Prelude with minimal mods?
If I go with something like an F22 series, will I need a new transmission and ECU?
Do all B20x series use the same transmission?
Is there a site other than www.tigerjapanese.com that has great prices on used engines?
Thanks in advance! :-)
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