Why did Hashem instruct Moshe here to fix the Paroches underneath the hooks and to then bring the Aron into the Kodesh Kodshim, considering that the Mishkan had not even been built yet?
Ramban: Hashem is not issuing Moshe current instructions here; He is merely informing him that he should place the Paroches underneath the hooks so that, when he moves the Aron there, it will divide between the Kodesh and the Kodesh Kodshim.
Seeing as the Mishkan had only one curtain that divided the Kodesh and the Kodesh Kodashim, why, in the second Beis-Hamikdash were there two?
Yoma, 51b: Because, bearing in mind that in the first Beis-Hamikdash, the division was made via a wall of an Amah thick (known as the Amah T'raksin, they were not sure whether that Amah belonged to the Kodesh or to the Kodesh Kodashim, so they put up two curtains leaving the Amah in between as a Safek. 1
See Torah Temimah, note 26, who elaborates.
Why does the Torah refer here to the Heichal as "haKodesh"?
Menachos, 27b: To teach us that the entire Heichal is called "Kodesh".
