What is the ruling on congratulating others on the arrival of Ramadan?
Congratulating others on the arrival of Ramadan is permissible.
If someone does it to express their love for worship and the blessings of Ramadan, and congratulates their fellow Muslim, they have done something good.
The Prophet ﷺ said: "Shall I not tell you something that, if you do it, you will love one another? Spread peace (Salam) among yourselves." [Narrated by Muslim]
Giving Salam is a prayer for peace and safety.
Is it permissible to participate in an Udhiyah?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Regarding the sacrificial offering (Udhiyah), if it is a sheep or a goat, it only avails for one person. However, if it is a cow or a camel, it avails for seven people. It is permissible for the seven participants to have different intentions; for example, some may intend the sacrifice (Udhiyah), some the ’Aqiqah (sacrifice for a newborn), and others may simply intend to obtain meat.
It is stated in Hashiyat Qalyubi ‘ala Sharh al-Mahalli (Vol.4/P.256) and in Bushra al-Karim (p. 706):
"If one slaughters a camel or a cow on behalf of seven... it is permissible. Likewise, it is permissible if some of them intend their seventh for meat, and others intend their seventh for ’Aqiqah." And Allah the Almighty knows best.
What is the virtue of performing ‘Umrah in Ramadan?
Ibn ‘Abbas narrated: "When the Prophet ﷺ returned from his Hajj, he said to Umm Sinan Al-Ansariyyah: ‘What prevented you from performing Hajj?’ She replied: ‘Abu So-and-so (referring to her husband) had two camels—he performed Hajj on one of them, and the other was used to irrigate our land.’ The Prophet ﷺ then said: ‘Performing ‘Umrah in Ramadan is equivalent to Hajj with me.’" [Narrated by Al-Bukhari]
The Prophet ﷺ also said: "An ‘Umrah in Ramadan is equivalent to a Hajj." [Narrated by Al-Tirmidhi]
For those who miss the opportunity to perform ‘Umrah in Ramadan, there are many other ways to earn great rewards. One of them is praying Fajr in congregation, then remaining in the mosque remembering Allah until sunrise, and praying two rak‘ahs.
The Prophet ﷺ said: "Whoever prays Fajr in congregation, then sits remembering Allah until the sun rises, and then prays two rak‘ahs, will receive the reward of a complete Hajj and ‘Umrah—complete, complete, complete." [Narrated by Al-Tirmidhi]
Is it acceptable to perform the Aqiqah for a male child by slaughtering and distributing the first sheep, and bringing the second one cooked from the restaurant?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
It is permissible to slaughter the first sheep with the intention of Aqiqah (the newborn's sacrificial offering) and distribute it entirely [uncooked], and to slaughter the second sheep and have it cooked at a restaurant to bring home for the household. However, it must be noted that it is obligatory to give some portion of the Aqiqah in charity to the poor, even if it is a small amount, though it is preferable to send the food cooked to them.
Buying a pre-cooked, ready-made sheep from a restaurant does not suffice as an Aqiqah. However, if an agreement is made with the restaurant to explicitly slaughter a sheep with the intention of Aqiqah for the newborn, and then cook it afterward, this is permissible.
In conclusion, slaughtering the sheep and distributing it with the intention of Aqiqah is permissible, and through it, the foundational prophetic tradition (Sunnah) is fulfilled. As for simply buying a cooked sheep from a restaurant that was not specifically slaughtered with the intention of Aqiqah, it will not count as such. Conversely, if the restaurant owner is commissioned (Wakala) to handle both the slaughtering and the cooking as an Aqiqah, it is valid—provided that a portion of it, even if small, is given in charity, which is estimated to be approximately half a kilogram of meat. And Allah the Almighty knows best.