Why does the Torah write "Kutanos" in the plural?
Yerushalmi, Yoma 3:6: to teach us the workers that they should make (a least) two unics for each Kohen. 1
See Torah Temimah, mnote 30.
Why does the Torah write "le'Chavod u'le'Sif'ares" specifically in connection with the Migba'os?
Rashbam: Because they are worn on the head (which is the king of the limbs).
What was the difference between the "Migba'as" of Kohen Hedyot's and the "Mitznefes" of the Kohen Gadol?
Rashi: They were one and the same.
Ramban (on Pasuk 31): The Mitznefes was a kind of turban that wound around and around the Kohen Gadol's head. The Migba'as spiraled upward. 1
Hadar Zekenim: The Mitznefes was smaller 2 than the Migba'as, because the Kohen Gadol's Tzitz extended a little on to the hair, to allow his Tefilin to be worn between the Tzitz and the Mitznefes. 3
Oznayim la'Toah: It was wide at the bottom and narrow on top (like the hats worn in the middle ages).
Riva (citing R. Eliyahu): A Kohen Gadol's is called Mitznefes, because it is like a Tz'nif (a loose turban), since he cannot make it taut. R. Tam of Orleans - a Kohen Hedyot can make it taut at the back, but not in the front - due to his Tefilin. A Kohen Gadol cannot make it taut even a the back, due to the threads that hold up the Tzitz (which apparently would be a Chatzitzah).
Surely he always wore a smaller Mitznefes even when he did not wear Tefilin - on Shabbos and Yom Tov (PF).
