1)

(a)The Tana of the Beraisa holds that all Chayvei Tevilah should Tovel on Yom Kippur - in order to be able to Daven (on account of 'Tevilas Ezra' - Ezra's Takanah that someone who is Tamei may not Daven or study Torah).

(b)A Nidah and a Yoledes Tovel on Kol Nidrei night. A Ba'al Keri who became Tamei after Minchah, may not Tovel - because, according to the Tana Kama, one Davens Ne'ilah after night in which case, someone who becomes Tamei after Minchah, has no need to Tovel.

(c)According to Rebbi Yosi, one may even Tovel after Minchah, too - in order to Daven Ne'ilah - since, in his opinion, the time for Ne'ilah is before night (not like Rav). (Note: According to Rav, the Tana Kama is the Tana who holds that Ne'ilah exempts one from Davening Ma'ariv, and whose opinion he personally follows; whereas Rebbi Yosi will hold like the Tana'im in the previous Beraisa, who maintain that the time to Daven Ne'ilah is before night - perhaps he is even the Tana Kama of that Beraisa.)

2)

(a)In a second Beraisa, the Rabanan and Rebbi Yosi seem to have switched their opinions - the Tana Kama permits Tevilah even after Minchah, whereas Rebbi Yosi forbids it. Rebbi Yosi forbide a Ba'al Keri to Tovel after Minchah - because that Beraisa speaks when the Tamei man has already Davened Ne'ilah.

(b)Even though we are speaking when the Tamei man had already Davened, the Rabanan (who are not the same Rabanan as those who argue with Rebbi Yosi in the previous Beraisa) nevertheless permit him to Tovel - because they hold 'Tevilah bi'Zemanah Mitzvah' (it is always a Mitzvah to Tovel as soon as it falls due - and the Tevilah of a Ba'al Keri falls due by day).

(c)Rebbi Yosi holds 'Tevilah bi'Zemanah Lav Mitzvah'.

(d)We reconcile this with a Beraisa in Shabbos, where Rebbi Yosi permits a Tevilas Mitzvah even with the Name of Hash-m written on his skin (even without a bull-rush tied around it) - because of 'Tevilah bi'Zemanah Mitzvah - by establishing the first Rebbi Yosi as Rebbi Yosi b'Rebbi Yehudah, and the second one as the more commonly known Rebbi Yosi (ben Chalafta).

3)

(a)Tevilah is not included in the Isur of erasing the Name of Hash-m - because it is not a positive act of erasing, and only causes the Name to become erased (known as 'Gerama').

(b)The Rabanan of Rebbi Yosi maintain that Tevilah bi'Zemanah Lav Mitzvah. Consequently, they insist that, even for a Tevilas Mitzvah, one ties a bull-rush around the Name of Hash-m - because, even in the event that he does not find one, he will be able to Tovel on the following day.

(c)Rebbi Yosi b'Rebbi Yehudah says 'Tevilah bi'Zemanah Lav Mitzvah' - with regard to a woman who went away pregnant and returned after having given birth. Beis Shamai and Beis Hillel, who both hold 'Tevilah bi'Zemanah Mitzvah', argue in Nidah over all the possible days that she is obligated to Tovel (because of their possibly being the forty-first day - for a boy, or the eighty-first - for a girl). According to Rebbi Yosi b'Rebbi Yehudah, she can wait until the very last day and Tovel then.

4)

(a)The Tana of another Beraisa permits someone who sees Keri on Yom Kippur to Tovel immediately, adding 've'la'Erev Yeshafshef'. This seems to be meaningless - as what is the point of wiping away the Keri after he has already Toveled.

(b)We therefore amend this to 'mi'ba'Erev Yeshafshef' - meaning that everyone should bathe himself on Erev Yom Kippur, to remove any potential Chatzitzah, in case he sees Keri on Yom Kippur and needs to Tovel.

5)

(a)According to the first Tana, seeing Keri on Yom Kippur is a sign - that all his sins are forgiven ('Yir'eh Zera, v'Ya'arich Yamim').

(b)When the second Tana says 'Avonosav Sedurim' - he means that all his sins are arranged, ready to be forgiven.

(c)Rebbi Yishmael b'Rebbi Yosi says that he should worry the entire year - because here he is practicing Inuy, and min ha'Shamayim, they are satisfying him with pleasure (like a servant who dilutes a jar of wine, and his master throws it back at him).

(d)Should he survive the year however, he is assured of going to Olam ha'Ba - because he must have a lot of merits that helped him to survive. Rav Nachman bar Yitzchak proves this - from the fact that in spite of that, when everybody else was 'hungry', he was forced to be 'satisfied', he survived the year. He must indeed be a big Tzadik.

6)

(a)When Rav Dimi arrived in Bavel, he said 'Meifish Chayei, Sagi u'Masgi', which, with reference to someone who sees Keri on Yom Kippur, means - 'He will live long and have many children and grandchildren'.

(b)The Pasuk "Yir'eh Zera, Ya'arich Yamim" ("Yir'eh Zera" seems to have a dual meaning) hints to this.