Seeing as the Sotah only drinks the water after the Minchah has been burned, as the Torah states clearly in Pasuk 26, why does the Pasuk insert it here?
Rashi: The Pasuk inserts it here to stress - via the phrase "u'Va'u vah ha'Mayim ha'Me'arerim" - that, although the Torah only mentions stomach and thighs, in fact, her whole body will be affected by the water. 1
Rashi: And it mentions stomach and thighs, because those are the limbs with which she began to sin.
What are the connotations of the word "le'Marim"?
Rashi: The Pasuk means that the cursing water that enter into her will be for her damaging and bitter.
Ramban: Refer to 5:18:5:4.
Targum Yonasan: It means that the examining water will enter into her as a curse.
What is the significance of the three things that examine the woman
Rashi (in Seifer ha'Pardeis): They represent the three things listed in Avos, 3:1, that prevent a person from sinning (which the Sotah did not apply) - the putrid drop (water) from which one came, the place of earth and worms to which one is going. and the fact that one will have to give Din ve'Cheshbon before the King of Kings. ("Vekasav lah es ha'A'alos").