Marrying a Christian woman without a wali (guardian) or witnesses

Her maternal uncle did her marriage contract in the presence of her brother without the knowledge of her father who does not pray

They committed zina and got married before they repented; do they have to do a new marriage contract?

Is it acceptable to stipulate a condition in the marriage contract that her husband should not inherit from her if she dies?

He did the marriage contract with her when she was pregnant as a result of zina, and now he is refusing to do a new marriage contract

A married Christian woman wants to become Muslim and marry a Muslim man

She wants to get married but her sons refuse

She does not have any male relatives on her father’s side; can her mother’s husband or her brother through her mother be her wali (guardian) for the purpose of marriage?

Ruling on a child born as the result of a marriage that was not officially documented

He married her in a ‘urfi marriage, then he divorced her three times. Is it permissible for him to marry her after that in a valid marriage without her first having been married to another husband?