1. There is a dispute in the Mishnah about when a girl may no longer do Mi'un.
2. There is a dispute about whether a girl who is a minor may do Chalitzah.
3. Rebbi Elazar: The law follows Rebbi Yehudah's opinion in the Mishnah (see #1).
4. Rava discusses a claim put forth by Iyov, and how Hashem answered his claim.
5. The Mishnah discusses how long the two hairs must be.
A BIT MORE
1. Tana Kama: She may not do Mi'un once she has two (relatively short) hairs. Rebbi Yehudah: She must have what looks like many such hairs before she may no longer do Mi'un. (The Gemara explains that they may be two hairs, but they must be very long).
2. Mishnah: She may not do Chalitzah; she must be an adult in order to do Chalitzah or Yibum. Rebbi Yosi: While a man must be an adult to perform Yibum or Chalitzah, a girl may be a minor and do Chalitzah.
3. However, Rebbi Yehudah admits that if she had relations with her husband after she had even two hairs, she may no longer do Mi'un. That act is like a new act of Kidushin that is done when she is old enough to accept Kidushin on her own.
4. When Iyov was having difficulty accepting his suffering, he said that perhaps Hashem confused Iyov with "Oyev" ("enemy"). Hashem answered that if He ensures that every hair in the head of a person has its own pore and does not grow from a different pore, then He certainly does not confuse "Iyov" with "Oyev"!
5. Rebbi Yishmael: One must be able to bend the top of each hair over so that it touches the root of the hair. Rebbi Eliezer: They must be long enough to be slightly held with the help of one's nail (smallest length). Rebbi Akiva: They must be long enough to be able to be cut with a scissors (longest amount).