Is the one offering the sacrifice liable if its meat spoils?
Praise be to Allah, and prayers and peace be upon our Master the Messenger of Allah.
If the meat (of the sacrifice) spoils due to the negligence of the one offering the sacrifice in preserving it, or due to improper storage, then he is liable to compensate for the portion due to the poor (which is estimated as half a kilogram of meat). If the sacrifice was a vowed (mandatory) one, then he is liable for all of it.
However, if he was not negligent, then there is no liability upon him, because its ruling is the ruling of a trust (like an item left in someone's care). And Allah Almighty knows best.
Is washing the private part after urinating (Istinjaa`) a condition, and is it done with water and soap, or with water only?
Istinjaa` is obligatory for removing impurity, and it can be done with toilet paper, or a stone, or water. It is preferable to do Istinjaa` first with paper, or stone, or the like, then to wash the private part with water until making sure that the impurity has been removed. Using soap is not a condition, but there is no harm in doing so provided that it is washed off with water. It is also permissible to use either water, or paper if impurity is removed by any.
What is the ruling on wiping the head during ablution from behind a barrier like a headscarf (hijab)?
The obligation in ablution is to wipe some of the head; it is not a condition to wipe all of it. As for one who has a turban or headscarf on their head, it is permissible for them to wipe over it after wiping a part of their head in any place. This is easily done at the front of the head. This means the woman begins by wiping the front of her head from under the headscarf, then completes the wiping to the back of the head from over the headscarf. If the woman wipes over the headscarf on her head and the moisture reaches the scalp or some hair within the boundaries of the head, it suffices for wiping the head. And Allah the Almighty knows best.
What is the ruling of Islamic Law on one who died owing debts and left no wealth? Is it obligatory upon the heirs to settle these debts?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
The general rule is that if a person dies owing rights to other people, such as debts, these are settled from his estate, if he left any wealth, before the estate is divided. The Prophet (peace and blessings be upon him) said: “The believer's soul is suspended by his debt until it is settled for him.” Graded ḥasan by al-Tirmidhī. Repayment of debts takes precedence over the heirs’ right to inheritance.
If the deceased left no estate, or left wealth that was insufficient to cover his debts, it is not obligatory for the heirs to pay from their own wealth, but it is recommended for them to do so, because the deceased’s dhimmah (legal liability) remains occupied by the debt. It is reported in some narrations that he remains held in suspension until his debt is paid, and it is not part of filial righteousness for a child to leave his father’s dhimmah burdened with debt.
All of the children may contribute to settling the debt on behalf of their father and cooperate in doing so, even in installments, according to their ability. And Allah Almighty knows best.