1. Yeah the gen 2 motor came out of the SW20, but the bellhousing would probably be from a SA63 Celica ?
2. 118kw for the aus delivered naturally aspirated model not sure about other markets though.
3. Not that hard to get forged internal for a 3S-GTE, but for 3S-GE you will probably have to go custom.
4. Gen 2 3S-GE is very strong and reliable. If mounted at the correct 15degree angle (or whatever angle they are usually on, i think it's about 15? maybe 30? I dunno).