What exactly is the first part of the Pasuk teaching us? On what conditions is the Kohen's daughter permitted to eat Terumah once again?
Rashi: The Torah is teaching us that she is permitted to return to her father's house to eat Terumah, 1 provided she becomes either widowed or divorced from her husband and provided she either did not bear him children 2 or the children that they had died, 3 (and provided she is not a Shomeres Yavam
Seeing as the bas-Kohen is included in "Y'lid Beiso" (in Pasuk 11), why does the Torah see fit to permit her to eat Terumah here?
Rashi (on the Beraisa of R. Yishmael): Since the Torah taught us a Chidush in connection with her (prohibiting her to eat Terumah once she marries a Zar), she leaves the realm of "Y'lid Beiso" until the Torah reinstates her. 1
Rashi #2: Refer to 22:13:1:1**.
Rashi: This is one of the thirteen principles of R. Yishmael - 'Something that was included in the Klal, and that then left the Klal to teach something new, it cannot be returned to the Klal, unless the Torah specifically reinstates it'.
Having already taught us that a Zar is forbidden to eat Terumah, why does the Torah repeat it here?