Why does the Mishkan need to be guarded?
Oznayim la'Torah (citing the commentaries at the befinning of Tamid): Due to the prestige of the Mishkan. (One canot compare a palace that is not guarded to one that is - Rambam). 1
See Oznayim la'Torah, who discusses the opinion of the commentaries who hold that the Mishkan had to be guarded day and night.
What do ?Mishmart?cha u?Mishmeres Kol ha?Ohel? incorporate?
Seforno: They incorporate the Kodesh Kodshim and the Kodesh, respectively ? which the Levi?im guarded from outside the boards of the Mishkan.
What is the definition of "K'lei ha'Kodesh" and "ha'Mizbe'ach" that are mentioned here?
Seforno: "Klei ha'Kodesh" refers to the three Keilim that are inside the Kodesh - the Menorah, the Shulchan and the Mizbach ha'Zahav - and ha?Mizbe?ach?, to the Mizbe'ach ha'Olah - even though it is outside the walls of the Mishkan.
What are the implctions of "Gam Heim Gam Atem"?
Arachin, 11a #1: It teaches us that the main Avodah of the Levi'im, like that of the Kohanim, concerns the Mizbe'ach - Shirah, which they performed whilst the Korban Tamid was being brought. 1
Arachin, 11a #2: It teaches us that a Kohen who perform the Avodah of the Levi'im, or vice-versa, is Chayav Misah. 2
