Is it permissible for the wife to give the Zakah (obligatory charity) of her money to her poor husband?
Yes, it is permissible for the wife to give from the Zakah of her money to her poor husband. And Allah Knows Best.
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 a person in a state of major impurity (junub) walking or eating before performing the ritual bath?
It is from the Sunnah for a Muslim to hasten to perform the ritual bath for major impurity. However, if he delays it, he does not sin provided he does not miss the prayer. It is permissible for the junub to walk, eat, drink, and sleep. It is recommended for him to perform ablution before these actions to reduce the state of impurity, although the best is for him to perform the ritual bath. And Allah the Almighty knows best.
What are the key differences between the 'aqīqah and the uḍḥiyyah?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
The following are the key differences between the 'aqīqah and the uḍḥiyyah:
First: The 'aqīqah is slaughtered as an act of drawing closer to Allah the Almighty and expressing gratitude for the blessing of a newborn child. The uḍḥiyyah, on the other hand, is slaughtered as an act of drawing closer to Allah and expressing gratitude to Him specifically during the days of slaughter (ayyām al-naḥr).
Second: The 'aqīqah is performed on the seventh day from the birth of the newborn, whereas the uḍḥiyyah is performed on Eid al-Aḍḥā and its time extends for three days after the Eid.
Third: The 'aqīqah is performed once in a lifetime for the newborn, whereas the uḍḥiyyah is recommended every year.
Fourth: It is Sunnah for the one intending to offer the uḍḥiyyah to refrain from cutting his hair and nails until after he has slaughtered. This is not a Sunnah for the one intending to perform the 'aqīqah.
Fifth: It is Sunnah for the 'aqīqah to be cooked and distributed to the poor in its cooked form. The uḍḥiyyah, by contrast, must be distributed as raw meat. And Allah Almighty knows best.