Please explain the following questions.
1. If a woman had been raped, how did she obtain a kesuvovah? Did this have to be reavealed before nisuin?
2. How was it possible to complete kedushin with a girl before she was as bogeress? If the mitzvah is procreation, it would not be possible. It would appear the act was merely for pleasure. Although Yitzchok married Rivka when she was three, at what age did they cohabit?
1. I'm not sure I understand your question. If a woman was Ne'ansah before she was married her Kesuvah is 100 and she has to reveal it before she gets married. If she doesn't it is a Mekach Ta'os and the Amoraim disagree if she forfiets the entire Kesuvah or merely the extra hundred.
If it occurred after the Erusin she receives the entire Kesuvah; however there is a Machlokes between R' Gamliel and R' Yehoshua upon whom lies the burden of proof (12b).
2. A person may not remain without a wife even if he has already fulfilled P'ru u'Rvu. See Even ha'Ezer 1. Even if he is unable to procreate he must not be without a wife.
In general, a Na'arah is already of childbearing age. As for Yitzchok, Tosfos in Yevamos 64a says that in earlier times women were able to bear children at a younger age.
Dov Zupnik