Why does the Torah insert the (otherwise superfluous) words "Veyatz'ah mi'Beiso"?
Sifri: To teah us that, in the case of divorce, it is the woman who is obligated to move house and not the man. 1
In order to compare Gerushin to Kidushin ("ve'Yatz'ah ve'Haysah") in all of the following issues: a. Just as a father can receive his daughter's Kidushin, 2 so too, can he receive her Get, (he has the authority to marry her off - Kesuvos, 47a) b. A woman can be acquired with a Sh'tar just as she is divorced with a Sh'tar (Kidushin, 5a); c. A Sh'tar Kidushin, like a Get, must be written Lish'mo and d. with the woman's knowledge (Kiduhin, 9b) 3 - like a Get, which must be written with the knowledge of the husband - who, like the woman who is being Makneh herself, is being Makneh the Sh'tar, e. Like by a Get, the woman can be acquired via her Shali'ach; f. Like a Get, a Sh'tar Kidushin that is written on what is attached, is Pasul; 4 g. Just as by a Get that the husband throws his wife in the street, she is divorced provided it is closer to her than to him, so too, in the equivalent case by Kidushin is she betrothed; h. Just as, if the husband says to his wife that she is permitted to the whole world except for P'loni, she is not divorced, 5 so too, if he betroths a woman and tells her that she is forbidden to the whole world except for P'loni, she is not betrothed.
Yerushalmi Yevamos, 9:5: To teach us - via the juxtaposition of "Vehaysah" to "Veyatz'ah" - that a married woman is only permitted to marry another man after she is divorced. 6
Why does the Torah insert the (otherwise superfluous) word "Vehalchah Vehaysah le'Ish Acher"?
Sifri: To teach us via the juxtaposition of "Vehaysah" to "Vehalchah" - that when a divorced woman marries another man, she is obligated to move away from the neighborhood where her ex-husband lives. 1
Oznayim la'Torah: It means that, after being divorced for the unpleasantries that she perpetrated, she moves to a location where she is not known and marries a man form there.
Refer to 24:1:151:1 and see Torah Temimah, note 64, who elaborates.
What are the implications of the word "Vehaysah le'Ish Acher"
Kesuvos, 46b: With reference to the three forms of Kidushin - Kesef, Sh'tar and Bi'ah (intimacy) - it implies that they are compared to one another and that, just as the girl's father acquires her Kesef Kidushin, 1 so too, does he have the right to betroth her via Kidushei Sh'tar and via Kidushei Bi'ah.
Kesuvos, 74a: See answer #1. And by he same token, if a man says to a girl that he is being Mekadesh her with intimacy on condition that her father agrees, the condition takes effect - despite the fact that the act cannot be performed by a Shali'ach 2 - since by Kidushei Kesef and Kidushei Sh'tar it can be performed by a Shali'ach.
Yevamos, 11b: It implies that if she merel had relations with another man, her husband is permitted to take her back. 3
What are the implications of "Vehaysah le'Ish Acher"?
Rashi: It implies that the second man is not in the same league as the first one - since he took into his house the wicked woman 1 whom the first man sent away. 2
Sotah, 5b: It implies "le'Ish Acher", 've'Lo le'Yavam' - to preclude a woman who contravened her husband's warning not to seclude herself with P'loni, and her husband died before taking her to the Beis-Hamikdash to drink the water - who is obligated to perform Chalitzah but not Yibum.
Gitin, 82b: It implies that the husband must permit her to marry any man - to preclude where he gave her a Get permittig her to marry any man except for P'loni. 3
Kidushin, 67b: It implies that the woman is permitted to marry someone who is a stranger to her, but not relatives who are subject to Kareis and on whom Kidushin will therefore not take effect. 4