Why did he say "Rumah Al ha'Shamayim Elokim"?
Rashi (57:6, from Shocher Tov 7:7): Remove Your Shechinah from the lower beings. They are not worthy that Your Shechinah be among them!
Radak: This is a metaphor. It is as if during Galus, He is not elevated above Shamayim to rule over the nations and rebuke them due to us - "Lamah Sihyeh k'Ish Nidham k'Gibor Lo Yuchal Lehoshi'a" (Yirmeyah 14:9), and so Hashem said about the salvation "Atah Aromem Atah Enasei" (Yeshayah 33:10), "Arum ba'Goyim Arum ba'Aretz" (above, 46:11).
Malbim (57:6): Send from Shamayim and save him. These words correspond to "Ekra lEi'lokim Elyon" (verse 3) - He is the First of all causes. The first cause for the salvation should be miraculous, above Shamayim, which pertains to natural conduct and the Ma'arachah.
Why does it say "v'Al Kol ha'Aretz Kevodecha"?
Radak: Show Your honor to the entire land.
Malbim (57:6): These words correspond to "la'Kel Gomer Alai" (57:3) - He is the Last of all causes. Also the last cause for the salvation should be directly from You, without an intermediary, so Your honor will be revealed in the entire land; the final result is on the land.
