Why does the Torah use the double Lashon "Im Mo'en Yema'en Avihah"?
Kesuvos, 39b: To teach us that the girl too, is permitted to refuse. 1
Targum Yonasan: To teach us that, if she is not fit 2 to marry him, he may not betroth her.
Kesuvos, 44: To teach us that if her father was alive when the man seduced her, the seducer is Chayav to pay K'nas. 3
Yerushalmi Kesuvos, 3:5: To obligate the seducer to pay K'nas even if he is prevented from marrying her 'bi'Yedei Shamayim. 4
Refer to Torah Temimah, note 165. Oznayim la'Torah: And the reason that the Torah mentions only her father specifically is because, having complied with the seducer, she will probably agree to marry him.
Even though, had she been a Yesomah when the man seduced her, he would have been exempt from paying K'nas. See Torah Temimah, note 166.
See Torah Temimah, note 167.
What is "Kesef Yishkol" referring to?
What are the connotations of "ke'Mohar ha'Besulos"
Rashi: It refers to the fifty Shekel K'nas that a rapist is obligated to pay the girl that he raped, 1
Hadar Zekenim: It hints to the Kesuvah of 200 Zuz for a Besulah. The letters Chaf Mem Hei Reish alludes to Kamah (Da'as Zekenim - Mohar)? Reish (its Gematriya is 200). R. Moshe - the Gematriya of k'Mohar (like it is pronounced, with a Vav) is 271, one more than that of 'Reish (200) Zuzim.'
Yerushalmi Kesuvos, 5:5: It teaches us that the inticer turns the K'nas into a Kesubah, since "Mohar" means Kesubah. 2
Oznayim la'Torah #1 (citing th Ha'amek Davar): From the root 'Maher' (quickly), it means that he should take the opportuning of making a quick Shiduch, without the preliminary courtship.
Oznayim la'Torah #2: It means that he should hurry to take the opportunity of marrying her, to avoid problems that will arise with furure Shiduchim when people refer to his his past behavior.
Why does the Torah write "ha'Besulos" and not simply 'Besulah'?
Kesuvos, 29b: To include in the Din of Chayvei La'avin (from "Besulos") and Chayvei Kerisos (from the 'Hey'). 1
See Torah Temimah, note 174 & 164.
Why does the Pasuk mention the monetary obligation only after the father's refusal to allow him to marry his daughter?
Rashi (Yevamos, 61a): Because in the event that the seducer marries her, he is exempt from paying.
How can she refuse the Kidushin of her father, seeing as he can be Mekadesh her Bal Korchah (against her will)?
Moshav Zekenim: If he enticed her Lo l'Shem Ishus, her refusal obligates him to pay a fine, even if he marries her. If he enticed her l'Shem Ishus, her refusal obligates him to pay Pegam, and he must be Mekadesh her again with her father's consent.
It seems that, due to the circumstances under which she is now set to marry the seducer, the Torah gives her the right to turn him down even against her father's wishes.