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.
Is supplicating in Qunoot, at times of affliction, during obligatory and voluntary prayer a Sunnah, and should it be done before Rukoo` (bowing), or after it?
At times of affliction, it is a Sunnah that Muslims supplicate in Qunoot after the final Rukoo` of each obligatory, or voluntary prayer as individuals, or in congregation.
Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.
What is the ruling on deliberately breaking the fast while being capable of fasting?
Whoever intentionally breaks their fast in Ramadan without a valid excuse has committed a major sin and bears great guilt. They must repent, seek forgiveness, refrain from eating and drinking for the rest of the day, and make up for that day after Ramadan.
They have lost an immense reward, which cannot be compensated even by fasting an entire lifetime as a voluntary act, because an obligatory fast cannot be equaled by voluntary fasting.
If the fast was broken through sexual intercourse, the person must:
● Make up for the missed fast (qada), and
● Perform kaffarah by fasting two consecutive months.
● If they are unable to do so, they must feed sixty needy people.