The time in the said marriage is the right of the husband and only he can forgo it. But it is permissible for the wife to make a condition in the contract that she acts on his behalf in this matter. She can then forgo the remaining time.
It is reported in the narrations that it is recommended to recite the Istighfar after the first prostration. It is not reported that it is recommended to do so after the second prostration.
If what you need can only be obtained in a larger quantity, then khums is not applicable on what remains from that. For example, if you need a notebook of 20 pages, but you could not find a 20-page notebook, and the closest to it is a 100-page notebook, then the unused part of the notebook will not be subject to khums. Similarly, if you need 20 pens, and you can purchase 20 pens without needing to buy 100 pens, then the unused pens will be subject to khums.
It is not permissible to have physical contact between non-mahram males and females after both have reached the age of religiously recognized adulthood.