What are the pillars of fasting?
The pillars of fasting are intention and abstaining from all nullifiers of fasting from dawn to sunset.
Is it permissible for an elderly person, a pregnant woman, or someone with a chronic illness to pay fidyah before Ramadan begins?
It is not permissible for an elderly person, a pregnant woman, or someone with a chronic illness to pay fidyah before Ramadan begins.
Additionally, it is not allowed to pay fidyah for more than one day in advance, because fidyah is a substitute for fasting, and fasting is not yet obligatory at that time.
However, it is permissible to pay fidyah for a single day in advance, by analogy with paying zakat up to one year in advance.
Is it permissible for a woman to sit with her brothers-in-law?
It is impermissible for a woman to sit with her brothers-in-law, and it is also impermissible for a person to have a Khulwa (seclusion) with his sister-in-law.
Is it permissible for a wife to give her money to her family as a charity, or a gift without asking her husband, or seeking his consent?
The wife has the right to give her money as a charity, or a gift to her family, or to other people after consulting her husband out of respect, and this is the meaning of treating on footing of kindness and equity. Therefore, if he wanted to stop her from helping her family, then there is no harm in not telling him.