Does having a wet dream during the day in Ramadan break the fast?
Having a wet dream during the day in Ramadan does not invalidate the fast. However, one must perform ghusl (ritual purification) to ensure they do not miss their prayers.
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.
What is the ruling on istibra' and how is it performed?
Istibra' (cleansing from urine) is recommended. It is for a person to ensure that nothing remains of urine in its passage before performing istinja'. Its method is: to clear the throat (or cough slightly), shake the penis (meaning to pass fingers along it to expel any remaining urine if needed), and walk a few steps to the extent that one thinks nothing of urine remains if walking is needed. Each person knows his own nature best. The preferred opinion is that this differs among people. The objective is for one to think that nothing remains in the urinary passage that he fears will exit later. And Allah the Almighty knows best.
What is the ruling on men wearing rings (those made of silver and of other metals, such as iron), and are there conditions for men wearing rings?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
It is sunnah for men to wear a silver ring on the right hand, following the practice of the Prophet (peace and blessings be upon him). It is reported in Ṣaḥīḥ al-Bukhārī, on the authority of Anas ibn Mālik (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) took a silver ring and had “Muḥammad Rasūl Allāh” engraved on it. He said: “I have taken a ring of silver and had ‘Muḥammad Rasūl Allāh’ engraved on it, so let no one engrave the like of its engraving.”
It is a condition that the silver ring not exceed the size customary in the local norm (ʿurf). If it does, that is extravagance (isrāf). A ring made of a metal other than silver, such as iron or copper, is permissible to wear without disapproval (karāhah), except gold, which is forbidden (ḥarām) for a man to wear.
It is stated in Mughnī al-Muḥtāj (Vol.1/p.586): “It is permissible, without disapproval, to wear a ring of iron or lead. It is sunnah for a man to wear a silver ring on the little finger of his right or left hand. Wearing it on the right is better, and it is permissible on the left, and on both together.”
It is also stated in Mughnī al-Muḥtāj (Vol.2/p.97): “It is lawful for him, that is, the man, and likewise the khunthā (person of indeterminate sex), indeed all the more so, to wear a ring of silver, by consensus (ijmāʿ), because the Prophet (peace and blessings be upon him) took a ring of silver, narrated by the two Shaykhs (al-Bukhārī and Muslim). Wearing it is in fact sunnah, whether on the right or the left, though the right is better according to the sound position, as stated in the chapter on clothing in al-Rawḍah… The Shāfiʿī jurists did not specify the permitted size of the ring, and they probably relied on custom (ʿurf), that is, the custom of that country and the habit of people of his standing in it. Whatever exceeds that is extravagance, as they said regarding a woman’s anklet. This is the reliable position (al-muʿtamad).” And Allah Almighty knows best.