What is the ruling on purchasing sacrificial animals and authorizing their slaughter via telephone?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is preferable for the one offering a sacrifice (udhiyah) to slaughter the animal himself, in adherence to the Sunnah, or to be present at the slaughter if possible.
It is valid to authorize a butcher to purchase a sacrificial animal on his behalf and slaughter it, regardless of whether the animal is owned by the butcher or the butcher is acting as an agent in its sale—according to the Hanbali school—provided that the butcher specifically designates and purchases the animal for the person offering the sacrifice before slaughtering it. And Allah Almighty knows best.
Is it permissible to offer mandatory prayer while sitting?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions. Standing up is a pillar in the mandatory prayer and the prayer is not valid without it unless one cannot do it. As for Nafila (supererogatory prayer), one can perform it in the state of sitting even if he/she can stand, but his/her reward is half the reward of the person who prays while standing if he/sh has no legal excuse for such an act. And Allah Knows Best.
Must a person refrain from eating for the rest of the day if they break a fast of a vow (nadhr) or a make up fast (qada)?
Whoever observes a vowed fast (nadhr) or a makeup fast (qada) is prohibited from breaking it without a valid excuse. If they break it without a legitimate reason, they are sinful.
However, they are not required to refrain from eating for the rest of the day, because such restraint is only required out of respect for the month of Ramadan, not for other types of fasting.
Is vomit among the nullifiers of Wudu (ablution)?
Vomit does not nullify Wudu, but it is a Najaasah (impurity) that requires rinsing the mouth and washing whatever became dirty by it since the prayer becomes valid only after the removal of Najaasah. And Allah Knows Best.