R. Yosi holds that a Zav who becomes Tamei on the seventh day is Metamei Mishkav and Moshav retroactively mid'Rabanan.
According to R. Yosi a woman can only become a Zavah Gedolah if she sees blood three days straight or if she sees three days in a row at twilight.
A Stam Nazir shaves and brings his Korbanos on the thirty-first day but if he shaves on the thirtieth day he is Yotzei.
If someone takes upon himself two consecutive Neziruyos he shaves for the first Nezirus on the thirty-first day and for the second Nezirus on the sixty-first.
If he shaves for the first Nezirus on the thirtieth day he may shave for the second Nezirus on the sixtieth day. (1)
The Tana Kama holds that if a Stam Nazir becomes Tamei on the thirtieth day he must recount his Nezirus.
R. Eliezer holds that if a Stam Nazir becomes Tamei on the thirtieth day he only must wait seven days before bringing his Korbanos.
If a person says he will be a Nazir for thirty days, if he becomes Tamei on the thirtieth day he must recount his Nezirus.
The Tana Kama says that if someone is a Nazir for 100 days and he becomes Tamei on the one hundredth day he must recount his Nezirus.
R. Eliezer says that if he becomes Tamei on the one hundredth day he only must recount 30 days. (2)
The Tana Kama says that if he becomes Tamei on the one hundred and first day he must recount thirty days. (3)
If someone takes upon himself Nezirus in a cemetery he does not have to bring a Korban Tum'ah. (4)
If he exits the cemetery and re-enters he must bring a Korban Tum'ah.
R. Eliezer says that he only brings a Korban Tum'ah if he re-enters the next day. (5)
R. Yochanan says that if someone takes on Nezirus in a cemetery he is a Nazir and if he drinks wine or cuts his hair he is punished with Malkus.
Reish Lakish says that he is not a Nazir and he must take on the Nezirus again when he exits the cemetery. (6)
A BIT MORE
1. If he shaves for the second Nezirus on the fifty-ninth day he is Yotzei b'Di'eved since the fifty-ninth day is the thirtieth day of the second Nezirus.
2. It is a Gezeiras ha'Kasuv according to R. Eliezer that if a Nazir becomes Tamei on the last day of his Nezirus that he only must recount thirty days.
3. R. Eliezer holds that he only must wait 7 days before he restarts his Nezirus.
4. The same would be true regarding someone who takes upon himself Nezirus while he is Tamei.
5. According to R. Eliezer if a Nazir becomes Tamei on the first day of his Nezirus he does not bring a Korban Tum'ah and after he becomes Tahor he only must count 29 days for his Nezirus since the first day also counts toward his 30 days of Nezirus.
6. If he delays taking on the Nezirus he transgresses the Isur of Bal Te'acher.
The Rambam says that a Nazir Tahor that makes himself Tamei to a Mes is punished with Malkus also for the prohibition of Bal Te'acher (delaying a Neder) because he is delaying his Nezirus Taharah with an action. So too if a person takes on Nezirus in a cemetery he is punished with Malkus also for the prohibition of Bal Te'acher. A Nazir who is Metam'ei himself is punished with Malkus for four Lavim: Lo Yeichal, Lo Yitamei, Bal Te'acher and Lo Tavo.
NEZIRUS IN A CEMETERY
If someone makes a Neder to be a Nazir in a cemetery, the Nezirus goes into effect. Even if he remains there for many days it does not count towards his Nezirus and he is punished with Malkus for remaining there. If he is warned not to become a Nazir in the cemetery he does not shave his hair upon exiting the cemetery. If he becomes Tamei in the cemetery to one of the Tum'os for which a Nazir would normally shave his hair, he does not shave his hair or bring a Korban Tum'ah. (Rambam Hilchos Nezirus 6:8)