I agree with Kotetsu on many points... and I don't understand why so many people don't accept Rachel's death. I mean... why is it so "horrible" that you want to rewrite it so she doesn't die? Personally, I like when some characters die (even near the middle of the story if they want, even when I like them (my 3 favorite characters in FMA, for example, die quite quickly after we meet them...)), it shows more "reality" to me. People die, it's a fact. In a war, in a battle, people die. In fact, I'd prefer a change with one character more in the band, who die near the middle...
More than changes, I'd prefer a longer end. KAA&MG always have problems with ends ^^' They're too short...
And of course fixing the mistakes.
For the changes of when characters appear etc. and even another end, it is possible when the story is adapted to another format. For example, if the Animorphs became a TVshow, I wouldn't care if the story wasn't exactly the same. In fact, I even prefer that, so I don't know exactly what will happen next
So forget the rewrite, hope for a TVshow
PS: Of course, I'm not against the fanfictions who "rewrite" the story. Why not? What they write could be the story in a parallel universe
It's fun, so I'm totally with that ^^