Can a woman leading other women in Tarawih prayer recite aloud?
Yes, a woman leading other women in Tarawih prayer is allowed to recite aloud, as long as no non-mahram (other than unmarriageable kin) men can hear her.
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]
What is the ruling on performing dry ablution (tayammum) instead of the ritual bath due to severe cold?
Whoever is sick such that he cannot use water, or finds the water cold and heating it is not possible, and the person would be harmed by using cold water, it is permissible for him to perform tayammum. He must make up what he prayed with tayammum, because this is a place where there is water. And Allah the Almighty knows best.
What is the ruling on selling sacrificial animals (udhiyah) described with specific attributes and authorizing an agent to slaughter them?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Selling sacrificial animals (udhiyah) that are described with specific attributes is permissible. This falls under the category of a salam sale (forward sale) if conducted using the terminology of salam, and under the category of a regular sale if not using the terminology of salam.
As for authorizing the seller to slaughter the sacrificial animal, the basic principle is that it is permissible, because the agent (wakil) stands in the place of the principal (muwakkil) in achieving his objective. This is a contract that the principal (the buyer) is entitled to perform himself, so authorizing another (the seller) to do so on his behalf is valid.
However, it is a condition for authorization to slaughter that the intention (niyyah) is present either at the time of slaughter or at the time of handing over the sacrificial animal to the agent. The basic principle is that the sacrificial animal must be specifically designated, as it is an act of worship. It is not required to designate it at the time of slaughter; rather, it is valid to do so before that.
It is permissible for the principal either to delegate the intention to the agent or to formulate it himself when authorizing the agent to slaughter. However, the sacrificial animal must be designated, even if at the time of slaughter, by the agent.
It is obligatory to designate the sacrificial animals so that each person offering a sacrifice receives his own specific animal. Therefore, charitable organizations and companies must take this into consideration and establish a specific mechanism that ensures no mixing of sacrificial animals occurs, so that each person offering a sacrifice receives his own designated animal. And Allah Almighty knows best.