Did they seriously not mention Fred's death??? That's like so important to the plot!

This is so hard to chose!

I want Fred's death, Wormy's death, Dumbledore's full backstory, I want them all!

Fred still does in the movie. You just don’t see it happen. His family still mourns over his corpse in the great hall.

Yes, but that's in the background. It doesn't really get explained in the movie.

There’s not much to explain. He died in the battle. The specifics don’t really matter. The purpose of showing his death in the book was to bring some closure to Percy’s story. Since Percy’s entire arc was cut from the movies, that scene would have been kind of pointless.

Kreacher's Tale was so important, why did they omit it in the movie?

Yes!

Tie between Kreacher’s and Dumbledore’s full stories

Yeah!