1)
Why does he say to the Rasha "you are a Tzadik"?
1.
Malbim: [The judge] flatters him.
2)
Why will nations curse him?
1.
Malbim: He destroys the foundations of Mishpat and Tzedek.
3)
Why does it add "Yiz'amuhu Le'umim"?
1.
Malbim: Le'umim have a special creed. They curse because he destroys the creed. Za'am is a punishment that comes via a curse. It is as if they specify his punishment. Amim have a creed and etiquette. They curse because he destroys the etiquette.