What are the ramifications of "v'Lo Yechalel Zar'o be'Amav"?
Rashi: Should he
father a child from one of the Pesulei Kehunah, he is Chalal (empty) from Kedushas Kehunah.
Ramban, Moshav Zekenim (both citing Kidushin, 78a): It is a second La'av, not to profane one's children, which is subject to an additional set of lashes.
The Kohen Gadol, or even a Kohen Hedyot.
See Sifsei Chachamim; and if it is girl, she is forbidden to marry a Kohen.
Ramban: "Lo Yikach" forbids Kidushin, but he is lashed for Kidushin only if he does Bi'ah (See Ramban). And the fact that the children are Chalalim is automatically understood.
Why does the Torah write "v'Lo Yechalel" and not "v'Lo Yachel"?
Rashi (in Yevamos, 44b): One 'Lamed' teaches us that the Pasul woman becomes a Chalalah, the other, that her child becomes a Chalal, too.
Rashi (Ibid, 15b): Others learn that she becomes a Chalalah from the word "be'Amav".