Why does the Torah insert the Parshah of the Ananei Kavod here followed by that of the trumpets?
Oznayim la'Torah: As an introduction to their departure from Har Sinai - in 10:13.
Why does the Torah insert the (otherwise superfluous) word "u've'Yom Hakim es ha'Mishkan"?
Shevu'os 15b: To teach us that one may not build the Beis-ha'Mikdash in the night. 1
See Torah Temimah, note 37.
What is the meaning of "ha'Mishkan le'Ohel ha'Eidus"?
Rashi: Although "Ohel" in the context of the Mishkan refers to the covering of goats-skin, here, with reference to the bottom curtains (which are called 'Mishkan') it means that they were made to cover (protect) the Luchos ha'Eidus.
Ramban: It means that the Cloud covered (not the entire Mishkan, but just) the "Ohel ha'Eidus" - to preclude the Chatzer.
What is the "Ohel ha'Eidus"?
Oznayim la'Torah: It is the Kodesh Kodashim which housed the Luchos ha'Eidus and above which the Cloud now rested.
Which cloud is "Kisah he'Anan" referring to and what is the significance of the fact that it rested on the "Ohel ha'Eidus"?
Oznayim la'Torah (based on the Yalkut Shimoni): The Cloud was the same one in which Hashem revealed himself to Yisrael on Har Sinai, and the fact that it returned now was testimony that Hashem had forgiven them for the sin of the Golden Calf - a sign as to how much He loved them. 1
See also Oznayim la'Torah DH 'le'Ohel ha'Eidus' who presents another interpretation of 'Ohel ha'Eidus', which explains why the Torah was now housed in the Mishkan.
Why does the Torah write "u?va?Erev Yih'yeh" (future) al ha'Mishkan?
Rashi: It means that the Cloud covered the Mishkan continually. 1
Rashi: And so it does throughout the Parshah. See also Rashi in Beshalach Sh'mos, 15:1 DH 'Az Yashir Moshe' - end of Dibur.
Why does the Torah repeat the word "ha'Mishkan" seven times in this Parshah (when, in most cases, it could just as well have written 'Alav')?
Ba'al ha'Turim: To hint at the seven 'Mishkanos' that were built ? in the Midbar, Gilgal, Shiloh, Nov, Giv'on, the first Beis-Hamikdash and the second Beis-Hamikdash.