Is the marriage contract considered valid if concluded at home by the marriage official (Ma`zon)?
Yes, it is valid as long as it is registered at the court.
Can someone who begins a voluntary fast break it?
It is preferable for someone who begins an act of worship not to break it.
Allah the Exalted has said {what means}: "and let not your [good] deeds come to nought!" [Muhammad/33].
However, if a person starts a voluntary fast (nafl) and needs to break it, they are going against what is preferable, but there is no sin upon them.
Is a woman`s prayer considered invalid if non-Mahrams (marriageable men) saw her offering it?
A woman`s prayer isn`t invalidated if non-Mahrams saw her offering it, but she had better pray in isolation.
Can a menstruating woman listen to the Quran from the radio or television?
Yes, a menstruating woman is allowed to listen to the Quran from the radio or television. What is forbidden for her is reciting the Quran and touching the Mus-haf, but listening is permissible—in fact, it is an act of worship.However, she should not repeat along with the Qur’an or try to keep pace with it.