1)
Having mentioned "min ha'Bakar" in Pasuk 3, why does the Torah need to add "ve'Chi Sa'aseh Ben Bakar ... "?
1.
Menachos, 90b: To confine Nesachim to Korb'nos Nedavah - to preclude the Se'irei Chatas that are brought on Yom-Tov from the realm of Nesachim. 1
2)
Why does the Torah insert the word "O Zavach"?
1.
Menachos, 91b: Refer to 15:3:5:2*. To teach us that someone who brings two Olos or two Shelamim, even one as a Neder and one as a Nedavah, is Chayav to bring one Nesech for each Korban. 1
1
See Torah Temimah, note 8.
3)
Why does the Torah insert the words "O Shelamim"?