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.
Is it incumbent on the fiancée to obey her fiancé?
When the woman settles in her husband`s house, it is incumbent on him to provide for her and it is incumbent on her to obey him. Before that, and if the marriage contract had been concluded, then she is lawfully his wife and thus she should abide by custom in treating him, but if the marriage contract hadn`t been concluded, then she should treat him as a non-Mahram (Marriageable).
How to perform the witr prayer in terms of connection (wasl) and separation (fasl)?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
The Witr prayer has several forms that vary in terms of virtue:
The First Form: Separating every two units (rak‘ah) with a Tashahhud and a Taslim (salutation). This is superior to connecting the units, even if it is only a single rak‘ah. This is based on the Hadith of ‘Aishah (may Allah be pleased with her): 'The Messenger of Allah ﷺ used to pray eleven units between the end of the ‘Isha prayer and dawn, performing the Taslim after every two units and performing Witr with a single unit.' (Related by al-Bukhari & Muslim).
The Second Form: Connecting the units with only one final Tashahhud at the very end.
The Third Form: Connecting with two Tashahhuds—meaning reciting the Tashahhud before the final unit without performing the Taslim, then standing to complete the final unit. This form is considered the lowest in rank so that the Witr prayer remains distinct from the obligatory Maghrib prayer, as stated in the Hadith: 'Do not make the Witr resemble the Maghrib prayer.' (Narrated by Al-Daraqutni, who stated its narrators are trustworthy).
It is stated in Bushra al-Karim Sharh al-Muqaddimah al-Hadramiyyah: 'It is permissible to connect [the Witr] with one Tashahhud in the final unit—which is better—or with two Tashahhuds in the last two units, as both methods are established in Sahih Muslim from the actions of the Prophet ﷺ. In the connected method, more than two Tashahhuds are prohibited. Furthermore, separating (al-Fasl) is better than connecting (al-Wasl) if the number of units is the same, because the Hadiths supporting it are more numerous and it involves more devotional actions.' And Allah the Exalted knows best."
What is the virtue of Laylat al-Qadr?
It is enough to know its great status that Allah revealed an entire surah about it—Surah Al-Qadr. Moreover, the Quran was first revealed on this night.
Allah says {what means}:
"We have indeed revealed this (Message) in the Night of Power: And what will explain to thee what the night of power is? The Night of Power is better than a thousand months. Therein come down the angels and the Spirit by Allah's permission, on every errand: Peace!... This until the rise of morn!" [Al-Qadr/1-5]
The Prophet ﷺ taught us to observe I‘tikaf in the last ten nights of Ramadan, seeking Laylat al-Qadr. Whoever worships Allah and revives this night will receive the reward of worshiping for a thousand months—excluding Laylat al-Qadr itself.