What are the implications of "be'Chol Makom"?
Rashi: It implies that Ma'aser may even be eaten in a cemetery.
What is the latter half of the Pasuk coming to teach us?
Rashi: Refer to 3:8:1:1*.
Moshav Zekenim (citing R. Eliezer of Garmaiza): If the Levi'im were to receive a portion, they would work the land. Now that they work for Hashem, Ma'aser is their portion from [what is received from] working the land.
Sifri: It is teaching us that a Levi is only elgible to receive Ma'aser Rishon if he performs all the Avodos of a Levi - but not if he declines to fulfil even one of them.
Why does the Torah insert the (otherwise superfluous) word "Atem u'Veischem"?