1)
Why does the Torah add the word "Lachem Matanah Nesunim la'Hashem"?
1.
Rashi: In order to confine the service of the Levi'im to matters concerning the Mishkan 1 - but not as personal valets.
2.
Seforno: It means that Hashem handed the Levi'im to the Kohanim as a gift, to perform any task that they ask them to perform in the Mishkan
3.
Sifri: To teach us that it is to Hashem that the Levi?im are given, and not to the Kohanim. 2