What is the Islamic ruling on one who was unable to fast and then regained the ability?
He is not required to make up the fast (Qada) even if he becomes capable of it; whether he regained the ability to fast after paying the fidya (feeding a needy person for each day of missed fasting) or before it, because he was liable for paying it in the first place, so it remains binding upon him. However, if he delayed paying it beyond the first year, nothing is required of him due to the delay. If he is unable to pay it, it does not remain as a debt upon him. And Allah the Exalted knows best.
What is the Sharia basis of the Udhiyah?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
The Sharia basis of the Udhiyah (sacrificial offering) is firmly established through the Quran, the Sunnah, and the Consensus (Ijma') of the Muslims:
1. Evidence from the Holy Quran
Allah the Exalted says {what means}: "And the camels and cattle We have appointed for you as among the symbols of Allah; for you therein is good." [Al-Hajj/36]. He also says {what means}: "So pray to your Lord and sacrifice [to Him alone]" [Al-Kawthar/2]. According to the most well-known scholarly interpretations of this verse, "prayer" refers to the Eid prayer, and "sacrifice" refers to the slaughtering of the Udhiyah.
2. Evidence from the Sunnah
Al-Bara' bin 'Azib (may Allah be pleased with him) narrated that the Prophet ﷺ said: "The first thing we start with on this day of ours is to pray, then we return and sacrifice. Whoever does that has followed our Sunnah, and whoever slaughters before [the prayer], it is merely meat he has provided for his family; it is not part of the ritual sacrifice in any way" [Reported by Bukhari & Muslim].
Anas (may Allah be pleased with him) narrated: "The Prophet ﷺ sacrificed two white rams with horns. He slaughtered them with his own hand, mentioned the name of Allah (Tasmiyah), and said the Takbir" [Reported by Bukhari & Muslim].
3. Evidence from Scholarly Consensus (Ijma')
The Muslims have reached a unanimous consensus on the Sharia basis of the Udhiyah, and no one among the scholars has disagreed with this. [Al-Sherbini, Mughni al-Muhtaj, Vol.6/P.122].And Allah the Exalted knows best.
A man wishes to offer more than one uḍḥiyah (sacrificial offering), and intends by these sacrifices "on behalf of everyone whom Allah and His Messenger love." Is this intention valid?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
The uḍḥiyah (sacrificial offering) is not valid with this intention, because if the sacrificial animal is from sheep or goats, it suffices for one person only; and if it is from cattle or camels, it suffices for seven persons.
However, one may sacrifice it on his own behalf, and then gift the equivalent of its reward to whomever he wishes.
Imam ar-Ramlī (raḥimahullāh) says: "Ash-Shāfi‘ī (raḍiyallāhu ‘anh) said: It is within the vastness of Allah's bounty, the Exalted, that He rewards the one giving charity as well. From this, the scholars of the madhhab said: it is recommended for a person to intend the charity on behalf of his parents, for example — for Allah, the Exalted, will reward them, without this diminishing his own reward in any way." He then relates, as the relied-upon position, the permissibility of saying: "O Allah, convey the reward of what I have recited specifically to so-and-so, and to the Muslims generally." Az-Zarkashī said: "For reward varies in degree — its highest form is what one designates specifically, and its lowest form is what one dedicates generally [alongside others]." [End of quote from Nihāyat al-Muḥtāj]. And Allah, the Exalted, knows best.
What is the semi-circular structure attached to the Holy Kabah?
The semi-circular structure attached to the Holy Kabah is Hijr Al-Kabah (is a low wall originally part of the Kabah) and passing behind it is an obligation while making Tawaf because it is a part of the Holy Kabah. And Allah Knows Best.