Question: It never shows the clues to Kat, Rory, or Eugine and Clear's deaths, can someone please tell me what they are?
Answer: Eugene And Clear die at the same time because when Eugene was plugged up to the ventilator it sparked a fuse and caused the whole hospital to go up in flames, leading Kimberly to drive the emergency van into the river trying to drown herself.
Question: How did Thomas and Kimberly die?
Chosen answer: In the alternate ending of Final Destination 3, a newspaper blows by, revealing Kimberly and Burke ran into each other at a hardware store and a Camaro (belonging to Evan) ran through the store, knocking them into a nearby woodchipper. Kimberly's coat was tangled and was snatched into the machine. Burke attempted to save her, and both were dismembered.
Answer: No, Thomas wouldn't have died first because it was explained that Death was going backwards since everyone that died in the first movie made some people miss their death date, so he had to tie up the loose ends.
Question: Was the whole pileup because death tried to kill the survivors of the pileup? I mean he tried to fix their earlier survival due to the survivors of flight 180. I don't get the whole relation of the survivors of the pileup to the survivors of flight 180.
Answer: There is a scene later on where several of the characters realise they were 'supposed to die' in the first film but were spared because Death tied up the loose ends from the people who got off 180. They are loosely linked to the survivors of the first film, yes. Death is catching up in this film by causing the pile up, but because of the girls premonition, they basically cheated death twice.
Question: When Kimberly's friends died first in her vision she and her friends died last, but why were they killed before everyone in reality?
Answer: Kimberly and her friends died last in the premonition. By not getting on the highway, they're cheating death already. The diesel ends up on its way to kill Kimberly and her friends, but the cop pulls Kimberly out of the way, causing her to cheat death again.
Answer: I'm not sure of a very logical explanation for this, but it should be noted that the premonitions in the films are not 100% accurate as the accidents are not caused by Death itself and may not be based on reality. They are just premonitions that the characters have of an impending accident that happens due to some unfortunate circumstances such as malfunction or improper precautions. In short, It is merely Death's job to clean up those who manage to cheat death in these misfortunes. He plays no part in causing the accident itself.
Then why do several characters talk about Death stalking them? Or the fact that the chances of somebody strangling themselves in a bathtub, for example, are one in a million? Or what about Death's design, the signs, and Death's list?
Question: Why does Alex die before Clear? Wasn't she supposed to be next after Carter? I mean, Alex was supposed to die first but Carter intervened making death repeat the cycle according to the path of the explosion which included Carter dying first, then Clear second and finally Alex. Why didn't this happen?
Chosen answer: His death happened between movies. We don't know how many times they intervened with each other before he finally was killed.
Answer: In the movie clear tells the others she and Alex saved each other countless times, however if you pause the movie and enlarge the scenes where it's flashing all the news paper articles it tells you that Alex was killed by a falling brick. I do believe Alex pushed clear out of the way of the brick.
Answer: Death works backwards now in this movie.
Question: Why was Evan interviewed separately from the other "survivors"? Why is he so special; I thought all he did was win the lottery?
Answer: You thought correctly. He did only win the lottery. We only see Evan interviewed separately. It's just possible that he was last to be interviewed. Kimberly and the others were being babysat by Officer Burke, so it's likely they were interviewed before Evan. I think that all or any witness would be interviewed separately whatever the circumstances.
Question: Why did the nurse drown Kimberly in her dream? What connection do the baby, nurse and Kimberly have?
Answer: Dr Kallarjian (I think that's the correct spelling) looks as though she is attempting to murder Kimberly in her premonition. Kimberly herself says a nurse was trying to choke her. As we later see, the medical professional is just trying to resuscitate Kimberly, she just has a bizarre look on her face, like she wants to murder Kimberly. As to your second question, only new life (Isabella's baby) can defeat death.
Question: Why did the boy at the end die? At the barbecue, they tell the story of how Rory saved the boy from the news van and realise since Rory intervened when he wasn't supposed to be alive, the boy is on the list. But if all of them had died in the original pile up, they would not have crashed in the field, the news van wouldn't have been there, so the boy wouldn't have been in danger.
Answer: As stated in this film the survivors of the highway crash were all supposed to be somewhere where they would have died, but the flight survivors started a chain reaction that prevented their deaths. We could assume that the boy was also supposed to die at some point but his death was intervened once before and again when Rory saved him. So "Death" was still catching up.
Chosen answer: Eugene's death had no clues I know of, but Clear and Rory's did, Rory's clue was with Nora's. The trophy's shadow is segmented, giving it a divided look, Rory ends up divided to pieces by the barbed fence. As for Clear, Bludworth hints at it with his comment "such fire you have now".