Will He literally create new Shamayim and Eretz?
Refer to 65:17:1:1-4 and the note there.
Why does it say "Asher Ani Oseh"?
Radak: I keep them in their new condition.
Why does it say "Lefanai"?
Radak: I am the reason why they last.
What is the meaning of "Ken Ya'amod Zar'achem v'Shimchem"?
Radak: You, that the Ge'ulah will be in your days, do not think that your children after you will be exiled from their land and their name will be lost in Galus. The good that you will have will last forever for your children "ki'Ymei ha'Shamayim Al ha'Aretz" (Devarim 11:21). The name of Yisrael will never be lost, and they will not be exiled again, like the Goyim who came with Gog and Magog intended to fight against Yerushalayim, exile Yisrael and make their name perish. No! Your seed will endure like Shamayim and Eretz.
Malbim: The new Shamayim and Eretz will not have any change or loss. So your seed will not be eradicated via killing or the sword, and your name will not cease via a change of creed to idolatry. You will remain will happiness of the body and Nefesh.
