I think as far as the time travel stuff goes, you just have to suspend your disbelief for a bit. I mean yeah, he could have gone back earlier, but... then there would be no plot lol. I mean time travel is a HARD power to work with because it can basically be a cure-all (like, why didn't Hiro just go back in time AGAIN and leave Adam alone so he never would have become evil?) and you kind of have to think, ok, it doesn't really make sense but... it's also a show about people with superpowers ;D

What I'd really love is for the writers to fit something in about how time travel isn't as easy as it seems... expand on the whole 'butterfly effect' thing. Like, maybe even if Peter had come back and explained things to Nathan so he never gave that speech, something even worse could have happened. WHO KNOWS! ... my brain hurts :S