Is it permissible for a wife to refuse to go to bed with her husband (for sexual intercourse)?
It isn`t permissible for her to do so unless for a sound reason.
Is it permissible to offer mandatory prayer while sitting?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions. Standing up is a pillar in the mandatory prayer and the prayer is not valid without it unless one cannot do it. As for Nafila (supererogatory prayer), one can perform it in the state of sitting even if he/she can stand, but his/her reward is half the reward of the person who prays while standing if he/sh has no legal excuse for such an act. And Allah Knows Best.
Is it permissible to appoint a proxy for the sacrificial offering outside Jordan?
In the name of Allah; all praise is due to Allah, and peace and blessings be upon the Messenger of Allah.
It is permissible to appoint a proxy—whether an individual or a charitable organization—to perform the sacrificial slaughter (Udhiyah) on one’s behalf, even if it is carried out in a country other than that of the donor. This is conditional upon the proxy’s adherence to the established requirements of the Udhiyah, including the animal’s age, its freedom from physical defects, the designated timing of the slaughter, and the proper distribution of the meat.
However, it is preferable for the one offering the sacrifice to perform the slaughter personally, in order to attain the full reward and blessings of the act. And Allah (Exalted be He) knows best.
Where should a woman following her husband or another man in prayer stand?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
If a single woman prays with a man—whether she is his wife or a non-mahram (Ajnabiyyah)—the Sunnah is for her to stand behind the Imam and be shielded by him. If the Imam is leading both a man and a woman, the man should stand to the Imam's right, and the woman should stand behind the male follower (Muqtadi). In this way, she is shielded from the Imam by the male follower and remains at a distance from the follower and his line of sight. And Allah the Exalted knows best.