Conditions for the validity of Nikaah

Q: Please advise on the below scenario as well as questions. Insha Allah I am getting married in December in Cape Town, and I am from natal. The wedding and walima will be taking place in Cape Town. The Imam will perform the nikah at the house, as the nearest masjid is far away from the house. Is this allowed in Islaam? or does the nikah have to take place in the Masjid. For us to have the Walima, what are the requirements that need to take place. May Allah Ta'ala reward you for your assistance.

Q: Is it permissible in Islam to perform nikaah without the presence of parents and family but to have only friends present to act as witnesses, etc?

Q: I did nikkah with a girl who is above 18 years old. The nikaah was recited by her cousin who is younger than her. Four witnesses were my friends who were unknown to her. We didn't register our nikkah. Is our nikaah valid?

Q: I am living abroad and I want to save myself from zina. Can I marry for a month?  My partner is also ready.

Q: Does it matter in nikaah paper in which someone intentionally writes his cast wrong? Does it effect the nikaah?

Q: If a non Muslim does Nikaah with full faith and later on out of financial crisis gets irritated and speaks ill about Allah and Islam. Does his Nikah become invalid due to his rejection of faith?

Q: Will the nikaah be valid if the boy and girl conduct the nikaah alone without the presence of witnesses?

Q: I am a Muslim woman married to a Christian man. We have four kids together, and for the last six years, I have been living like a Christian. However, my heart was not wholeheartedly there. My heart was always towards being a Muslim and my children too were not happy. I returned to being Muslim now but I don't know what to do. Can you please help me?

Q: My friend married a guy through court marriage. Why? To protect themselves from committing sins. But when they told their parents after about a month, the girls parents lashed out and said that the Nikaah is invalid. So they accepted. Now the father of the girl has placed conditions for the boy that if he accomplishes them, they will gladly have them wedded. But the parents are only doing this to kill time. What must they do? Since the boy is getting angry and wants to bring in the police. Though we all know that is not right.