Is it permissible for one who sacrifices on behalf of another, with the latter's permission, to eat from the sacrifice?
It is permissible for someone who sacrificed on behalf of another with their permission to eat from it with their permission, and they stand in their place (act as their representative) in distributing it.
It is stated in Nihayat al-Muhtaj ila Sharh al-Minhaj (Vol.8/P.141): "And he—meaning the one sacrificing on his own behalf, provided he has not apostatized—has the right to eat from a voluntary sacrifice and his sacrificial gift; rather, it is recommended. As for an obligatory sacrifice, it is forbidden for him to eat from it, whether it was designated as such initially or as a liability in his dhimmah. And excluded by what has preceded is if he sacrifices on behalf of another, or if he apostatized, then it is not permissible for him to eat from it, just as it is absolutely impermissible to feed a disbeliever from it."(The text I found indicates the impermissibility of eating) ???
And it is stated in Hashiyat al-Jamal ‘ala Sharh al-Manhaj (Vol.5/P.262): "If a person offers a sacrifice on behalf of a living person with their permission, does he act as their representative in distributing it—on the grounds that permission to sacrifice is permission to distribute it—or does it depend on their explicit permission? This requires consideration, but the first view is not far-fetched." And Allah the Almighty knows best.
Is it permissible for a person to give the Zakah (obligatory charity) to his daughter-in-law?
Yes, it is permissible for a person to give the Zakah to his daughter-in-law if she was poor, and none provided for particularly by whom are obliged to provide for her. And Allah Knows Best.
In the Sharia-compliant viewing at a prospective bride (*al-naẓrah al-sharʿiyyah*), is it permissible for the man to see the woman without a veil (*ḥijāb*)?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
It is sunnah for the suitor to see the woman he is seeking to marry within the limits the Sharīʿah permits, namely looking at the face and the hands (palms and backs), based on the saying of the Prophet (peace and blessings be upon him): “Look at her, for it is more likely to bring about harmony between you.” Narrated by al-Tirmidhī.
The suitor may also ask one of the women to look at the woman he is seeking to marry. In that case, she is permitted to see of her what she is normally permitted to see, which is not limited to the face and hands, and she then describes these matters to the suitor. It is narrated on the authority of Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) sent Umm Sulaym to look at a girl, and said: “Smell her breath, and look at her heels.” Narrated by Aḥmad in his Musnad.
It is stated in Tuḥfat al-Muḥtāj (Vol.7/p.192): “For one who cannot easily look, or does not wish to look himself, it is sunnah to send someone who is permitted to look at her, to observe her and describe her to him, even regarding what he himself is not permitted to look at. He thereby gains through the sending what he would not gain through looking. Because of the added need for this, it is excepted from the prohibition of a woman describing another woman to a man.”
The permissibility of looking is conditional upon his resolve to marry her once he is able to, his predominant assumption that his proposal will be accepted, and his assumption that the woman is free of marriage and of a waiting period (ʿiddah). Otherwise, looking is forbidden.
Accordingly, it is not permissible for the suitor to look at anything other than the face and hands. He may ask one of his maḥram women, such as his mother or sister, to see the woman unveiled, and the Sharia-compliant viewing (of a prospective bride) must take place in the presence of one of the woman’s maḥrams. And Allah Almighty knows best.
If someone regularly fasts the six days of Shawwal, are they obligated to fast them every year?
A person is not obligated to fast the six days of Shawwal every year, even if they have made it a habit. However, someone who regularly performs a good deed should not abandon it as long as they are able.