What does "be'Einav" mean?
Rashi: It means that the Nega retained its appearance and its size. 1
Ramban (citing Toras Kohanim), Da'as Zekenim: It means that the appearance of the Nega did not change in the eyes of the Kohen. 2
What if the Nega spread after the first week?
Rashi: If the Nega spread after the first week, the Kohen declares him Tamei. 1
As implied by the words of the Pasuk.
What is "Mispachas"?
Rashi: "Mispachas" is the name of a Tahor plague.