Why does it say "Lech Imi Bo va'Chadarecha"?
Rashi #1: This is Hashem's answer to the Navi. Come with Me in your rooms - Batei Midrashos and Batei Kenesiyos.
Rashi #2 (from Tanchuma): Contemplate your deeds in the chambers of your heart.
Radak: The verse applies to the war of Gog and Magog. There will be affliction for Yisrael for a short time. It is a metaphor. "Come with me in your room, and close the door after you" - hide (be protected) via good deeds and full Teshuvah.
Why does it say "u'Sgor Delasecha Ba'adecha"?
Rashi citing Targum Yonasan: Do good deeds that will protect on you.
Rashi citing Tanchuma: Guard the doors of your mouth; do not question Midas ha'Din.
Radak: Refer to 26:20:1:3.
What do we learn from "Chavi Chim'at Rega Ad Ya'avor Za'am"?
Brachos 7a: This teaches that Hashem's wrath is a Rega 1 (about 1/15th of a second).
Rashi: Hide a little until the anger passes. Really, I will pay your haters. .
Radak #1: In a short time, the anger will pass and the good will be saved - "Kol ha'Nimtza Chasuv ba'Sefer" (Daniel 12:1). Chavi is feminine (wait); it refers to Ami. Am is usually masculine, but sometimes it is feminine, e.g. "Madu'a Shovevah ha'Am ha'Zeh 2 " (Yirmeyah 8:5), "v'Chatas 3 Amecha" (Shemos 5:16).
Radak #2: Chavi is a noun. Its grammatical form is like Shevi and Tzevi.
7a: Alternatively, we learn from "Ki Rega b'Apo" (Tehilim 30:6).
Am is feminine (Shovevah) and masculine (ha'Zeh) in this verse. (PF)
Ibn Ezra (Shemos 5:16); V'Chatas is a verb, in the feminine past; the Vov switches it to the future.