What the implications of "Ki Avodas ha'Kodesh aleihem"?
Rashi and Seforno: It implies that K'has carried the Aron, the Shulchan and the other Keilim, which were intrinsically holy 1 - which is why they carried them on their shoulders and not on wagons.
Seforno: As opposed to the B'nei Gershon and the B'nei Merari, who only carried the components of the Mishkan.
What can we learn from "ba'Kasef Yisa'u"?
(Rashi (in Shabbos 92a): It teaches us that 'Someone who carries on Shabbos is Chayav irrespective of whether he carries with his right hand or his left hand, in his bosom or on his shoulders. 1
Refer also to 4:16:1:1**.
" .. ki Avodas ha'Kodesh Aleihem ba'Kasef Yisa'u". Why does the Torah ninsert the (otherwise superfluous) word "Yisa'u"?
Arachin 11a: "Yisa'u" is a Lashon of singing - a hint that the Levi'im needed to sing (when the Korban Tamid was brought). 1
See Torah Temimah , note 7.
Why does the Torah write "ba'Kasef" (on the shoulders) and not 'be'Kasef' (on their shoulders)?
Panim Yafos (in Bamidbar 7:9): Because one Levi stood outside the poles (on the left), and one stood between the poles. 1
Refer also to Sh'mos 30:4:151:1,2 & 4 and note.
