What is the meaning of "Gavi Nizrech"?
Rashi #1: Detach your hair 1 . This is like "va'Yagaz Salvim" (Bamidbar 11:31), "va'Yagaz Es Rosho" (Iyov 1:20). Radak - growth of hair is called Nezer, because a Nazir grows his hair. This is like "Karchi va'Gozi Al Bnei Ta'anugayich" (Michah 1:16). Cast away the Nezer that was glory for you. Cast it to the earth to mourn. It is feminine, corresponding to Keneses Yisrael.
Rashi #2: Nizrech is your crown, an expression of grandeur. Also Targum Yonasan 2 and Menachem explain like this.
Why should the lamentation be on high places?
Malbim: It should be publicized; you have no hope.
What is the meaning of "va'Yitosh"?
Rashi: He abandoned. Malbim - it was not a temporary matter. He despised the nation, due to idolatry.
What is "Dor Evraso"?
Radak: This generation, on which He poured His anger.
Radak citing Targum Yonasan: The generation that transgressed His word.
