Does sacrificing one sheep avail for the entire household?
In the Name of Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
Offering an Udhiyah (sacrificial offering) is a communal Sunnah (Sunnah Kifayah) for members of the same household, provided that their financial maintenance is undertaken by a single provider. By "communal Sunnah," we mean that when one person performs it, the religious recommendation is fulfilled on behalf of the entire household, though the spiritual reward itself belongs uniquely to the one who offered it.
Therefore, if any member of the household performs the sacrifice—even if it is someone who is not legally responsible for the household's expenses, such as the wife or one of the children—the recommendation is fulfilled for everyone in that home. However, the reward does not automatically extend to the other members unless the person offering the sacrifice explicitly intends to share the reward with them—similar to how performing a funeral prayer (Janazah) fulfills the communal obligation for everyone, yet the specific reward is earned by those who actually prayed.
Additionally, a single sacrifice is sufficient for a man who is married to more than one wife. And Allah the Almighty Knows Best.
How is night prayer offered?
Night prayer is offering voluntary prayer after Maghrib and before Fajr (Dawn). As for Tahajjud, it is offering voluntary prayer at night after waking up voluntarily, and for Allah`s sake as He Says (What means): "And pray in the small watches of the morning: (it would be) an additional prayer (or spiritual profit) for thee: soon will thy Lord raise thee to a Station of Praise and Glory!" [Al-Isra`/79]. Offering Tahajjud is better than offering voluntary prayer before going to bed.
Is it enough to say Tasbeeh (Saying Subhaana Rabbiya Al-‘Atheem during Rukoo`, and saying Subhaana Rabbiya Al-A‘laa during Sujood ) once, or twice during Rukoo`(Bowing in prayer) and Sujood (Prostration)?
All perfect praise be to Allah, The Lord of The Worlds Yes, saying Tasbeeh once during Rukoo` and Sujood is enough, provided that the worshiper`s attentiveness of the heart isn`t undermined during each. As regards the recompense, it depends on the number of Tasbeeh. And Allah Knows Best.
What is the ruling on eating from one`s Udhiyah?
In the Name of Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The Udhiyah (sacrificial offering) is divided into two categories: the vowed sacrifice (Al-Mandhurah) and the voluntary sacrifice (Al-Tatawwu').
First: The Vowed Sacrifice (Al-Mandhurah)
This refers to a sacrifice that has become strictly obligatory due to a formal vow (Nadr). It is completely impermissible for the person offering it, or any members of their family whom they are financially obligated to maintain, to eat any of its meat or fat. Furthermore, it is unlawful for them to personally benefit from its hide, wool, or any other part of it. If they happen to eat any portion of it, the offerer is legally obligated to give an equivalent amount of meat or its monetary value to charity. (As noted in Tuhfat al-Muhtaj by Imam Ibn Hajar al-Haytami,Vol. 9/P.364).
Second: The Voluntary Sacrifice (Al-Tatawwu’)
This is a recommended, non-obligatory sacrifice. The person offering it is fully permitted to eat from its meat, distribute portions as charity to the poor, and give pieces as gifts to those who are well-off. However, it remains a mandatory requirement to donate at least a minor portion of it to charity; this should not be less than approximately half a kilogram of raw, uncooked meat. And Allah the Almighty Knows Best.