1) Revan was not above good and evil. The quest for power made him go over to the dark side, and he probably thought he could take on the True Sith after uniting the Republic forcibly. I'm not going to say he couldn't, as there's no proof he could or could not, I'm just pointing something out. Heck, Jolee and Kreia are the only ones I consider above good and evil.
2) Yes, the Jedi were pretty short-sighted with the Mando Wars, and yes, that made them look like jerks and hypocrites, but who said the Jedi were perfect?
3) If someone invaded your country, you wouldn't say "We won't fight them because they look different and that would make us discrimatory". The Sith invaded first. The Republic, naturally, had to fight back. And knowing the Sith tendency to kill everything in sight, then I'd consider killing Sith justice. It's the equivalent of giving the death penalty to a person who committed war crimes.
"There is no such thing as coincidence, only inevitability" - xxxHoLiC
"Justice? But I don't serve justice, Watson, I serve the truth." - Sherlock Holmes