It used to be believed that orcas did mate for life(monogamous), but we now know they do not. As for the revenge part, there was a report dealing with a female whose calf had been killed. The people in the boat were afraid the mother would kill them. She followed them for a long time.
"Do All Things For God's Glory"-1 Corinthians 10:31
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The film is loaded with fictions concerning marine mammals and orcas, simply to propel and validate its storyline. The next 'Jaws' movie that came out ascribed the exact same emotional and intellectual processes to killer sharks as a means of validating its storyline. Stories about sea creatures seeking revenge are as old as the Flood, and are merely an example of Man exporting his value systems to the High Seas in an attempt to explain a foreign environment; these include ancient moral codes, and ideas about marriage.

Do they see humans as almost "retarded"?
No. Unfortunately, whales don't have access to IMDB.
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Do they see humans as almost "retarded"?
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The scene you are referring to did not indicate any such thing. The whale simply was trying to destroy property and it happened to be a gasoline pipe. The spreading gasoline started a fire.
"Do All Things For God's Glory"-1 Corinthians 10:31
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Unless you mean mating for life with several females, like polygamy.

Yeah. There are more females than males. So no, they don't mate for life.
"Because females can live for up to ninety years, it is not uncommon for four or even five generations to travel together. These matrilineal groups are highly stable. Individuals split off from their matrilineal group only for up to a few hours at a time, in order to mate or forage. No permanent casting-out of an individual from a matriline has ever been recorded."
And as far as smelling.. I do believe they 'taste', rather then smell. But really, its about the same. Ever notice when your nose is stuffed, you cant taste as well?

Regarding mating, I always thought there were less males than females in the group, so how could they mate for life?

Can whales smell? I always thought the nose had become just a breathing device.

Those who have been in contact with gasoline fires could be able to associate the scent with fire couldn't they?
Made You Look

Not that I know of.
Off course that part was just film.

Do they also have advanced knowledge of gasoline and it's effect on spreading fire?

They don't mate for life.
Period.