Where did Aharon place the Ketores?
Oznayim la'Torah #1: He placed the pan containing the Ketores on the ground in between the dead and the living - to form a barrier between the Mal'ach ha'Maves and the living. 1
Oznayim la'Torah #2 (citing the Tanchuma): He threw it on the face of the Mal'ach ha'Maves. 2
How did Moshe know that the Ketores stops plagues?
Shabbos, 89a: When he ascended to the Heaven and every angel befriended him and gave him something, the Mal'ach ha'Maves taught him that the Ketores stops plagues. 1
See Torah Temimah, citing Shabbos, 89a and note 7.
What are the implications of "Vayiten es ha'Ketores Vayechaper al ha'Am"?
Zevachim, 88b: It implies that the Ketores atones. The bi-daily Ketores that is brought in private in the Heichal on the Mizbe'ach ha'Zahav, atones for the sin of Lashon ha'Ra that is spoken furtively. 1
The atonement for Lashon ha'Ra that is spoken publicly, was attained by the Me'il of the Kohen Gadol ('Yavo Davar she'be'Kol Viyechaper al Ma'aseh Kol'. See Torah Temimah, note 8.
Seeing as they spoke Lashon ha'Ra publicly, how could the Ketores, which only works by Lashon ha'Ra that is spoken furtively - atone for them?
Oznayim la'Torah #1: In order to form a barrier between the Mal'ach ha'Maves and the living 1 or to throw it on the face of the Mal'ach ha'Maves. 2
Oznayim la'Torah #2: In order to present the Mal'ach ha'Maves from crossing over to the living and killing them.
Oznayim la'Torah #2: In order to demonstrate to the people that the Ketores is not the source of death. 3
Because, due to the severity of the sin, they were punished by a plague, and the Me'il of the Kohen Gadol - Refer to 17:12:2:1* - would not have sufficed.
Why did Aharon have to take the Ketores outside the Azarah - which is strictly prohibited by all Korbanos (See Oznayim la'Torah)?
Why does the Torah switch from "ha'Eidah" - in the previous Pasuk to "ha'Kahal"?
Refer to 17:10:1:3**.
