Answer:
Elie meant it as-- like stated in the excerpt-- as revenge against the concentration camp that held him.
Explanation:
He was glad because no longer could anyone be held there anymore, and it was a sign of freedom, and hope.
No, I don't think the animals did the right thing by getting rid of farmer Jones.
This final chapter depicts the complete transformation (not only in name) from Animal Farm to Manor Farm. There will never be a "retirement home" for old animals (as evidenced by Clover), and the pigs come to resemble their human oppressors to the degree that "it was impossible to say which was which."
The completion of the second windmill marks not the rebirth of Snowball's utopian vision, but a further linking of the animals and humans: Used not for a dynamo but instead for milling corn (and thus making money), the windmill's symbolic meaning has (like everything else) been reversed and corrupted. Animal Farm is now inexorably tied to its human neighbors in terms of commerce and atmosphere.
When Ivan developed an illness, his character developed from being self-centered to being compassionate. By facing his own death, he began to examine his life. Gerasim, the one who helps Ivan during his sickness, was also a factor to his character development.