How will the ruins be built from you?
Radak: Just like evil deeds destroy the land, good deeds settle it. The good deeds that come from you will build what was ruined for a long time.
Malbim: You will fix the old ruins - evil and false Emunos, mindsets and deeds.
What are "Mosedei Dor va'Dor"?
Radak: The foundations that fell in the generations.
Malbim: You will establish fixed foundations in every generation, of creed, Emunah and conduct.
Who will call you "Goder Peretz", and why?
Radak: The world will call you so, for in your merit and good deeds, the breaches will be fenced.
Radak citing Targum Yonasan: [You are called] those who fulfill the proper Torah.
Malbim: It is because you built the old ruins (refer to 58:12:1:2).
What is the meaning of "Meshovev Nesivos Lasheves"?
Rashi citing Targum Yonasan: He returns Resha'im to Torah, the Yishuv (settlement) of the world.
Radak: When the land is destroyed, the roads are desolate; no one passes on them - "Darchei Tziyon Avelos mi'Bli Ba'ei Mo'ed" (Eichah 1:4). You will return the roads to be settled, that people will go on them, for the cities will be settled.
Malbim: You established fixed foundations (refer to 58:12:2:2) - those who teach the ways of life will return via your paths.