What are the implications of the words "Kol Y'mei Nizro"?
Rambam (in Peirush ha'Mishnayos, 1:3: It implies days and not hours. Consequenly, someone who undertakes Nezirus for thirty days and one hour must keep thirty-one days Nezirus. 1
Sifri: Following "Ad M'los ha'Yamim" - in Pasuk 5 - which implies Nezirus with a time limit, it comes to extend the prohibition of shaving to a N'zir Olam. 2
Having written Kadosh Yih'yeh Gadeil Pera Se'ar Rosho" - in Pasuk 5 ? why does the Torah write here "Kadosh Hu la'Hashem"?
Rashi, Targum Onkelos and Targum Yonasan: It extends the Kedushah on to the Nazir's body - which explains why he is not allowed to become Tamei Meis.
Seforno: To teach us that the Nazir is elevated to a higher plane, rendering him fit to issue rulings like leaders of the generation. 1
Seforno: Which is why Elkanah was happy to give his consent, when the angel instructed his wife Chanah, to declare his son Shmuel a Nazir from birth - See Shmuel 1, 1:23.
Why does the Kedushah come first on to the head and then on to the body?
Oznayim la'Torah: Because, although the heart is the physical center of the body, the center of spirituality is the head - and the purpose of Nezirus is to live on a higher plane of spirituality. 1
Refer to 6:15:1.1:1.