Is the marriage contract considered valid if concluded at home by the marriage official (Ma`zon)?
Yes, it is valid as long as it is registered at the court.
Is it valid to perform the obligatory prayer while sitting?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Standing (Al-Qiyam) while having the ability to do so is one of the pillars (Arkan) of the prayer; the obligatory (Faridah) prayer is not valid without it. However, whoever is unable to stand may pray sitting down. As for voluntary (Nafilah) prayers, it is permissible to pray them sitting even if one is able to stand, but the one sitting receives half the reward of the one who prays standing. And Allah the Exalted knows best.
Is it permissible to consume the meat of a sacrifice (Dhabihah) offered as an act of devotion to Allah, seeking His protection for my family?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is permissible to eat from this sacrifice, and the reward [for it] is according to what is given to the poor. And Allah the Exalted knows best.
Is Zakah (obligatory charity) obligatory on indebted merchant?
Debt doesn`t abrogate the dueness of Zakah, thus a debtor who has money, articles of merchandise, or other Zakah funds at his disposal should pay their Zakah.