What are the connotations of "ve'Lo Yih'yeh che'Korach ve'cha'Adaso"?
Rashi and Ramban #1: It means that the sign on the Mizbe'ach shall serve as a reminder ... in order that the sin of Korach and his congregation will not recur.
Ramban #2 and Targum Yonasan: It means that no man should be so arrogant as to dispute the Kehunah like Korach and his congregation, because ultimately he will be stricken, though not like Korach and his band of followers - with fire (or by being swallowed up under the earth- Targum Yonasan), but by contracting Tzara'as. 1
What does the Torah mean when it writes "Ka'asher Diber be'Yad Moshe Lo"?
Rashi #2 (citing the Midrash): "be'Yad Moshe" is a hint that in future, anyone who starts up with the Kehunah will be stricken with Tzara'as. 4
Ramban, Rashbam, Da'as Zekenim and Hadar Zekenim: With reference to Pasuk 4, he meant that Elazar removed the copper pans just as Hashem had told him via Moshe. 5
Rosh (on 16:25, citing Sanhedrin, 110a): Anyone who persists in an argument is deserving to receive Tzara'as. 6
Rashi: Whenever the word "Li, Lo or Lahem" follows Dibur, it translates (not as 'to', but) as 'about'.
Rashi (citing Midrash): Or about Korach.
Rashi: Which is why the Torah says here that 'no Zar, who is not from the seed of Aharon, may approach to bring the Ketores'.
Rashi: Just as Moshe's hand was on Har Sinai - Refer to note on answer #4. Indeed, that is what happened to King Uziyah who was stricken with Tzara'as on his forehead when he attempted to bring the Ketores - See Melachim, 26:19.
And the word "Lo" implies "Lo", 'le'Hana'aso' - for his benefit (Refer to Bereishis, 12:1:2:1) since the copper plates would remind the people not to tamper with the Kehunah Gedolah - and he (Elazar) was destined to become the next Kohen Gadol. See Oznayim la'Torah.
Rosh (Ibid.): Which we learn via a Gezeirah Shavah "be'Yad" from "Yado Metzora'as ka'Shaleg" - in Sh'mos 4:6. Refer to note 1 on answer #2