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 permissible for one who sacrifices on behalf of another, with the latter's permission, to eat from the sacrifice?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is permissible for one who sacrifices on behalf of another with his permission to eat from the sacrifice with his permission, and he takes his place in distributing its meat.
It is stated in Hashiyat al-Jamal 'ala Sharh al-Minhaj (Vol.5/P.262): 'If a person sacrifices on behalf of a living individual with his permission, does he take the place of that individual in distributing the meat, because permission for the sacrifice implies permission for distribution, or does it depend on explicit permission? There is room for consideration, but the former view is not far-fetched.' And Allah Almighty knows best."
What should a person, who doubts the validity of his Wudu, or over performs it, do?
One who doubts the validity of his/her Wudu while performing it should redo it until he/she is certain of having attained purity. But, if doubt was after having performed Wudu, then he/she should not pay attention to that as doubt after the end of an act of worship does not count. This is of course in case doubt was within the reasonable limits since once it goes beyond that, it becomes a whispering of the Shaytaan (devil) which he/she should ignore as the Wudu is valid.
Which is better during the day in Ramadan: reciting the Quran or performing voluntary prayers?
A Muslim should establish a daily schedule for reciting the Quran in Ramadan.
Once they have completed their daily portion (known as a wird or hizb), they can engage in other acts of worship, including voluntary prayers (nawafil). Prayer itself is called "Quran", because a significant part of it involves reciting the Quran.
Allah says: "BE CONSTANT in [thy] prayer from the time when the sun has passed its zenith till the darkness of night, and [be ever mindful of its] recitation at dawn: for, behold, the recitation [of prayer] at dawn is indeed witnessed [by all that is holy]." [Al-Isra`/78]