The commentators disagree on how to explain the words that he said as well as their meaning. It seems that he says that G-d runs the world with total justice. Rambam says that Elihu was correct in his statement about G-d. However, Others say that Elihu only repeated what the other three had already said. Others say that his statements were blasphemy and that he is beyond redemption and has no appropriate Tshuva.
All views seem tenable.
The answer is very simple. The book begins with telling us how righteous Iyov is. We then see G-d praising Iyov about how good he is. Iyov did not even question G-d when his children were killed and his wealth destroyed. After this The Persecutor asks G-d to damage Iyov's body.