Why does the Torah juxtapose the Parshah of Nega'im beside that of Yoledes?
Moshav Zekenim (12:8) #1: If one is not careful [to observe] the laws of Yoledes and Nidah 1 (which was mentioned with Yoledes), he brings on his children Tzara'as, "B'Or Besaro" is a compound noun; Besaro refers to children. 2 Seforno - Nega'im generally result when the [father's] Zera was not purified from the blood of Nidus (i.e. they had relations when she was Nidah). 3
Moshav Zekenim (12:8) #2: Nega'im is written next to Korbanos [Yoledes], to teach that if one deceives the Kohen (and asks him to offer a Chatas for Bi'as Nidah b'Shogeg, and really, he was Mezid), his children will be Metzora'im, to publicize his sin. "[Al Titen Es Picha Lachati Es Besarecha] vAl Tomar Lifnei ha'Mal'ach Ki Shegagah Hi" (Koheles 5:5), Kohanim are called angels - "Sifsei Chohen
Moshav Zekenim: If a Nidah has Bi'ah with her husband, her children will be stricken with Tzara'as for 20 generations; one who is not careful about this, in the end he will be get Tzara'as. Tanchuma (Metzora 1) - if one has Bi'ah on the first day of Nidah, the child will be a Metzora for 10 years; on the second day, 20 years
What are Se'es, Sapachas and Baheres"?
Rashi and Seforno: They are three different categories of Nega'im, one whiter than the other. 1
Rashbam (from Shavu'os, 6b): Sapachas is a secondary appearance. Se'es and Baheres are primary appearances; each has a secondary appearance.
Hadar Zekenim: According to simple meaning, Se'es and Sapachas are Avos 2 (primary appearances).
What are the appearances of Se'es, Sapachas and Baheres?
Nega'im 1:1: Baheres is as bright as snow; its secondary appearance is like the lime of the Heichal. Chachamim say, Se'es is as white as wool; its secondary appearance is like an egg shell. R. Meir reverses the last two.
What does the Torah mean when it writes "v'Huva el Aharon ha'Kohen ... "?
Seforno: 'He will be brought' (the Huf'al) indicates that the person comes to a place for something to be done to him, 1 as opposed to where he goes to do something, where the Torah writes 'he will come' (in the Kal). 2
Why did Hashem require Kohanim to rule about Tzara'as?
Seforno #1 (5): It is a Gezeiras ha'Kasuv that the Tum'ah and Taharah of Nega'im are placed under the jurisdiction of the Kohen, 1 who will teach the Metzora to do Teshuvah on his sins and to pray, as well as praying on his behalf. 2
Seforno #2 (5): Since the Kohanim were placed in charge of Nega'im, they would master the various appearances and be able to distinguish between one Nega and another.
What does the Torah mean when it writes "ve'Huva el Aharon ha'Kohen ... "?
Seforno: 'He will be brought' (the Hof'al) indicates that the person comes to a place for something to be done to him, 1 as opposed to where he goes to do something, where the Torah writes 'he will come' (in the Kal). 2