Why does the Torah write "Kol asher Tzivah Hashem es Moshe, rather than "Kol asher Tzivah oso Moshe"?
Rashi and Ramban (citing Yerushalmi Pe'ah, 1:1): Because Betzalel did even what Moshe did not tell him - in that Moshe instructed him to manufacture first the Keilim and then to construct the Mishkan, whereas Betzalel reversed the order, 1 just as Hashem had instructed Moshe. 2
Because, he argued, it is customary (and logical) to first build the house and then to place the Keilim inside it; to which Moshe replied "be'Tzeil Keil Hayisa!" - 'You were in the shadow of Hashem!' [the acronym of his name]), adding that that was precisely what Hashem had taught him (Rashi, citing Berachos, 55a).
See Tosfos, Berachos, 55a.
Why did Moshe invert the order that Hashem had taught him - particularly bearing in mind that he had himself made a wooden Aron in which to place the Luchos which he was about to receive?
He was not conveying the order in which Betzalel was to make the Mishkan and the Keilim, he mentioned the Keilim first based on the order of importance. 1
Based in turn, on the mantra 'Sof Ma'aseh be'Machshavah Techilah'.
Why does the Torah write that Betzalel did everything ... ?
Ramban: It is not to preclude the wise-hearted men who worked together with him. 1 It is to point out that Betzalel not only taught them what to do, but that he also oversaw every aspect of the building and that the workers brought him everything that they did for inspection.