What is the meaning of "va'Yalet Panav"?
Rashi citing Targum Yonasan: He wrapped his face. This is like "Lutah ba'Simlah" (Shmuel I, 21:6). Radak - also Moshe did so - "va'Yaster Moshe Panav" (Shemos 3:6).
Radak: He (Eliyahu) covered his face. This is like "Lutah ba'Simlah" (Shmuel I, 21:6), "Pnei ha'Lot ha'Lot" (Yeshayah 25:7).
Malbim: Hashem covered his face. This is like "v'Sakosi Chapi Alecha" (Shemos 33:22).
Why did he stand at the opening of the cave?
Radak: So Hashem commanded him "Tzei v'Amadta va'Har" (verse 11).
Hashem already asked "Mah Lecha Fo Eliyahu" (verse 9). Why did He repeat this?
Malbim: Why don't you return to your mission to prophesize to the nation, and to rebuke without Kin'ah and great commotion?