1)
Why does the Torah repeat the word "be'Yom Sh'neim-Asar Yom"?
1.
Mo'ed Katan, 9a: To teach us that, just as the hours of the day are consecutive, so too, were the twelve days of inauguration consecutive - and that consequently, building the Mishkan overrides Shabbos. 1
1
Refer to 7:48:151:1. See Torah Temimah, note 21 as to why the Gemara learns it from this Pasuk and not from Pasuk 72.