the fat guy (in the red tracksuit) is one of the Federal Avatiation Authority guys - he's in a suit in the jet engine removal scene witht the other FAA guys.
Cherita has a chrush on Donnie - hence his name on her notebook. Cherita decides not to deal with the world but instead to live as much as possible inside her head, hence the earmuffs and "chut up!", however she pays attention to what is happening with Donnie because she likes him. She is a great exposition of the 'loner' type - she sees so much because she is invisible. I agree with the statement about her demonstrating screwed up ideals of talent and beauty also. She is rejected because she is different, much as Donnie is.
If you go through the website it explains a lot, particularly the bit about the manipulated living and the manipulated dead (this is in the section that goes through Roberta Sparrow's [grandma Death] book). The basic plot construct is that a tangent universe has been created by the unexplained and unexplainable appearance of the jet engine. All the people in the movie have been dragged into this tangent universe. Two versions of the same universe cannot coexisit for long periods of time - the tangent universe will tear itslef apart and everyone will die ("they are in great danger")- thus the tangent universe must be collapsed in on itself. It is Donnie's job to do this - a role he has been assigned by a higher power (god?). He has been assigned this role due to his natural insight and his ability to accept things like "Frank" just turning up. Having this role gives him supernatural powers, allowing him to see the "fate tunnels" and to perform tasks such as burying the axe into the school mascot (the Mongrel).
The other main characters are the manipulated living or the manipulated dead. The manipulated dead are those who die within the tangent universe (which is the one in the movie). They are Frank and Gretchen. The higher power allows them to heavily influence and alter Donnie's actions. The manipulated living (the teachers, Jim Cunningham, Cherita, the shrink) are influenced by the higher power to act as guides, providing pointers as to what Donnie should do. The manipulated living and dead retain some memories of their time in the tangent universe when they are returned tot he real universe, hence everone waking up and having emotional reactions.
Donnie's fate is to collapse the tangent universe - to do this he needs his portal (the storm) and his vessel (the car), which is why he drives up to Carpathian Ridge. Dr. Monitoff (Noah Wyle) has already explained this to him. To collapse the tangent universe he must travel through time back to the event that caused the tangent to appear - the jet engine appearing from nowhere. The storm/tornado is the tangent universe begining to destroy itself Basically, Donnie collapsing the tangent universe results in the engine being tron off his mother's plane - the engine then becomes the vessel to go back in time, looping the tangent universe back into the real universe.
So why is Donnie laughing at the end, and why does he die? Perhaps he thought it was all a dream and didn't wake up without Frank there. Perhaps he was happy that he had stopped everything and everyone was safe, and was then happy to die. I don't think he necessarily had to die.
All this info comes from the Director's walkthrough and the website, as well as me watching the movie too many times. I could go on all day about little side issues and social commentaries smattered throughout the movie, but I think I've waffled on enough!
Smiley
