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.
Does undergoing surgery under anesthesia break the fast?
Anesthesia itself does not break the fast because anesthetic gases have no physical substance (jirm), and subcutaneous anesthesia injections do not reach the body cavity (jauf). However, this is on condition that the person is conscious at some point during the fasting hours:
● If they were awake at the beginning of the day, their fast remains valid.
● If they wake up even for a moment before sunset, their fast is also valid.
However, if the surgery involves the entry of foreign substances into the body cavity, their fast is invalidated, and they must make up for that day later.
What is the ruling on vomiting, and does it invalidate ablution?
Vomit is impure (najis). Its exit is not considered one of the nullifiers of ablution. However, the mouth must be washed and purified from it, and any that gets on clothing or the body must be washed for prayer, because prayer is not valid with impurity present on the body or clothing. And Allah the Almighty knows best.
What is the ruling on preparing food for someone who is not fasting in Ramadan?
It is forbidden to prepare food for someone who is breaking their fast without a valid excuse in Ramadan.
Doing so would be assisting in sin, and assisting in sin is itself a sin.
Allah says {what means}: "but help ye not one another in sin and rancour" [Al-Mai`dah/2]