What is the meaning of "Rasha Yir'eh v'Cha'as"?
Rashi: "V'Cha'as" is like Yich'as (he will be angry). This is why there is a Kamatz under the Chaf, and the last syllable is accented. (If it were a noun, it would have a Patach under the Chaf, and that syllable would be accented. - PF)
Radak: When the Rasha sees the Tzadik's honor, he is angry amidst great envy, and "Shinav Yacharok." If he was able to destroy him, he would!
Malbim: The Rasha sees the Tzadik's honor, and he is angry, but he cannot harm him at all, just he gnashes his teeth.
Why does it say "v'Namas"?
Radak: His heart melts from envy. This is like "v'Rekev Atzamos Kin'ah" (Mishlei 14:30).
What is the meaning of "Ta'avas Resha'im Toved"?
Radak #1: What the Resha'im desire, to see evil befall the Tzadik, that desire will be lost. He will never see the Tzadik's evil.
Radak #2: The good that Resha'im desire for themselves [will be lost], but it says about Tzadikim "v'Sa'avas Tzadikim Yiten" (Mishlei 10:24).