In different sources, it is explained that the sidra of Bamidbar Sinai be read before the holiday of Shavuos. The Netziv, in his introduction to sefer Bamidbar, mentions the fact that Bamidbar is called חומשהפקודים, as we call it in English; The book of Numbers. The main theme of this parasha is the counting of the Jewish People (the Midrash says that because we are precious to G-d, we are counted).
However, the Lubavitcher Rebbe (לקוטישיחות - ד) explains that parashas Bamidbar serves as an preparation for Shavuos, e.g. Matan Torah (The Giving of the Torah). The Rebbe explains that by being counted, the importance of the Jewish people was revealed to them in a tangible manner. (This sichah is somewhat eludicated in this book).
I was wondering. Are there other commentators that explain 1) if, 2) why parashas Bamidbar serves as a preparation for receiving the Torah on Shavuos.
The more sources, the better the answer :).