Why does the Torah again repeat "ve'Hishkah es ha'Mayim"?
Rashi: To teach us that, after the Parshah has been erased in the water, if she declines to drink it, the Kohen forces her to drink. 1
Sotah, 19b: To teach us that, even though, if the Sotah admits her guilt before the Name of Hashem has been erased she does not drink the water, once it has been erased, she is obligated to drink in spite of her admission.
See Sifsei Chachamim and Torah Temimah, note 122.
What are the implications of "ve'Haysah ha'Ishah le'Alah"?
Rashi (in Bereishis 26:4): Refer to 5:21:2:1. 1
See also Torah Temimah, note 123.
Why does the Torah add the (otherwise superfluous) words "Vehaysah ha?Ishah le?Alah be'Kerev Amah"?
Rashi: Because there is no comparison between someone who is put to shame in a place where he is known and someone who is put to shame in a place where he is not known.
Yerushalmi Sotah, 9:9: To teach us that, the miracle of the Mei Sotah, which ensured that Yisrael remained pure, would not apply when they are immoral. Hence, when adultery became rampant in Yisrael, the Mayim ha'Marim ceased to be effective. 1
See Torah Temimah, note 145.
Bearing in mind that in Pasuk 19 the Pasuk began with the side of merit, why here does it begin with the side of guilt?
Because there it is a Din connected with the procedure of Beis-Din 1 whereas here it begins with guilt because she has a Chezkas Tum'ah.
Oznayim la'Torah: Because before she took the oath, she is only Safek Tamei, whereas now, after taking the oath, and after causing the Name of Hashem to be erased, she is (all but) Vaday Tamei. 2
If a man and woman commit adultery and there are no witnesses, they die by drowning or by strangulation - which are similar to Chenek (the official punishment for adultery. Why here, do they die the horrible death described in the Pasuk?