What are the implications of "ve'Holech Meheirah"?
Oznayim la'Torah: It implies that once the Ketores was prepared and placed in the pan with the fire from the Mizbe'ach, Aharon was to hurry to save the sinners, but that the preparation itself was to be performed with the care and the Kavanos that the Ketores deserves.
Why did Moshe instruct Aharon to stop the plague specifically by means of the Ketores?
Rashi #1 (in Pasukf 13): To counter the people's claims that the Ketores is poison, since it killed Nadav, Avihu and the two hundred and fifty men. This would now demonstrate that the Ketores also stops plagues, and it is not the Ketores that kills, but our sins. 1
Rashi #2: Because, when Moshe ascended Har Sinai, the Mal'ach ha'Maves taught him the secret that the Ketores stops plagues. 2
Rashbam: To demonstrate that the same Ketores that kills those who are not Kohanim, gives life when it is in the hands of Kohanim - a proof that the Kohanim are the chosen tribe to perform the Avodah.
What is the significance of the term "Ketzef" that the Torah uses here?
Rashi (in Bamidbar): Refer to 1:53:2:1*.
Targum Yonasan: "Ketzef" is the name of one of the five destructive angels that were sent when Yisrael worshipped the Golden Calf. 1
Targum Yonasan (in Eikev Devarim, 9:19): Af, Cheimah, Ketzef, Mashchis and Charon (See also R. Bachye here).
Moshe told Aharon to rush, to stop the plague as soon as possible. Why did he need to say "Ki Yatza ha'Ketzef?"?
Rosh (in Tzav Vayikra, 8:2): When Moshe told him to take the Ketores, Aharon said 'My sons died for bringing human fire inside; Shall I take jHekdesh outside?' But when pointed out that people were dying even as they were speaking, he ran to burn the Ketores - prepared to [possibly] die for Yisrael.
