Conditions for the validity of Nikaah

Q: Can my brother in law be regarded as a witness at my sister's nikaah while I, the brother be the wali?

Q: If a boy texts message a girl saying, "Do you accept me in nikkah" and the girl texts back,"yes" and then the boy texts, "same here", and during this there is no witness on the girl's side but the girl does not know if there were witnesses on the boy's side or not. Is the nikaah valid?

Q: I am divorced and have two children. I had a court marriage in Pakistan but the nikah is not registered online. My husband told me not to tell the imam I am divorced because I didn’t have divorce papers and they needed proof. So I didn’t tell the imam I’m divorced and he wrote that I am a virgin on the papers. Is the nikah valid? I am from UK and my husband is in Pakistan.

Q: Can a groom himself serve as a wakeel for the bride in a nikaah ceremony?

Q: While getting married to someone you need at least two witnesses one male and two females or two males and one female. What if someone gets married in secret without telling anyone and they make Allah their witness and say qabul?

I read somewhere that if a mature girl and boy says qabul with the intention of making her/him their spouses, they'll eventually become husband and wife in the eyes of Allah. Is it true?

One of my cousins secretly went into a relationship and she considers that guy as her husband. He also considers her as his wife. So with a pure heart are they married in the eyes of Allah?

Q: If a young Muslim couple who are not married joke with each other and the man says let’s get married and the lady also jokes and says yes let’s do it, will the Nikaah be made?

Q: I did ijab o qbul without mehar and wali and without witness 8 years ago. There was no physical relation but I realized it is wrong. I left that boy now and my father is getting me married to my cousin. Should I get married to him or tell my father about the nikah 8 years ago?

Q: Will the nikaah be valid if it takes place in this manner:

The girl gives ijaazat to the boy to get her married. He then makes the nikaah in the proper manner with witnesses and the khutbah, etc., but he says she gave him permission and he accepts her in his nikaah.

Q: Can one get married without an Imaam and the partner male tells you, we can make nikaah as long as we know the duas. Is this permissible?

Q: Can a Sunni Moulana perform a nikaah between a Shia boy and Sunni girl?