I'm going to do my best to answer these, but keep in mind that I have less knowledge about this than many other here, so if you get conflicting answers, defer to them.
Film Questions
1. I'd actually use Harmy's workprints for his Despecialized V2 project, and eventually his final V2 product. AFAICT all home video versions of Star Wars have their color pretty badly mucked with. Harmy's actually using high-quality film scans as a reference, but since he cannot share those references, you can still benefit from them by using Harmy's project as a color reference.
2. Some contention here. I believe it's a recreation, but a really really painstakingly good one. Not significantly different.
3. I don't think so, aside from the weird John Williams spacing issues that weren't even present in all TR prints.
4. I believe so. Again for TR correctness, I'd go with Harmy's V2 workprints or his final product. Or you could contact You_Too, who created them.
5. I believe after.
I can't even try to answer the tech questions. I am a complete AviSynth novice.