1)
Seeing as the same Keruvim adorned the two sets of curtains, why were they divided into two sets?
1.
Seforno: One set covered the Kodesh, and the other, the Kodesh Kodshim. 1 They allude to angels of different levels of Kedushah. 2
1
And, based on the principle "Ma'alin ba'Kodesah ve'Lo Moridin', it was forbidden to switch their positions - just as it was forbidden to switch the position of the boards, which were marked. See Oznayim la'Torah on Pesukim 2-5. Refer also to 26:30:2:1 and to 25:4:1:1.
2
And the same applies to the goats'-hair curtains (See Seforno, Pasuk 9).
2)
How was each set of five curtains joined?
1.
Rashi: They were simply sewn together.