Custody of children

Q: I am divorced with two children (boy 9, daughter 7). My ex wife, has as I am led to believe, settled down perhaps made or not made nikah with the man I accused her with whilst we were married. I am not sure but I assume he is also divorced, he too has two kids of his own, also a daughter and a son I think maybe a year older than each of mine.

My first question is: What is the most authentic ruling regarding custody of children post divorce? Where and with whom and from what age should they reside with either mum or dad purely from what Shariah explains?

My second question and this is what haunts me: If tomorrow they all decide to move in together and lets say they are indeed married for purposes of this question, how does the mahram thing work? This man, is he mahram for my daughter firstly. Secondly, his children being exposed to my children, I fear abuse, bullying, sexual abuse(possibly! as a parent this thought lingers as they grow older and left alone), and my children being teased by his kids - that they only in that home because my ex wife married their father. Tomorrow if these step brothers or sisters or whatever they will be termed, if their natural father purchases or does something for my kids , they could get jealous or nasty towards my kids, maaf but all of these scenarios seem to be playing out, hence my questions. 

Q: Is they something a person can pray for when they have a court case? The case is regarding our son. My wife is trying to take my son away from me. He is doing hifz. He has done 9 juz. He is 9 years old. She doesn't care about all that.

Q: What does Allah say in the case of separation of husband and wife. The father wants to keep two children and gives the other two children to the mother even though the mother is willing to keep all the children but the father is forcefully keeping them..

Q: What is the ruling if 2 people are divorced Islamically. There's a son of 8 years old involved. I have tried amicabally to sort it out but what if my ex wife is trying to take full custody?

Also, what is the ruling if a girl is under the age of puberty?

Q: I want khula from my husband. I have a child and my husband wants that child. What should I do in this case?

Q: Currently my husband and I are separated after domestic violence and assault. I did leave myself after the physical abuse. I have now requested a faskh-e-nikah from Jamiatul Ulema. I have a 3 year old daughter.

1. I understand after the divorce, that shariah gives me custody until age 9/10 provided I do not remarry. What would be a fair amount of visitation/sleep over, with her best interest in mind in accordance with shariah for my husband with regard to our daughter considering her best interest with regard to her age and that I'm staying 400km from his home.

2. When we got married my husband agreed on giving me an allowance each month. Over the last several months he stopped giving me this allowance and he said he's saving it for me. Now he refuses to give me the R55000 that I had saved with him prior to the seperation.

a. Am I entitled to this money?

b. In the 5 month separation and iddah period that will inshallah soon follow, am I entitled to receive this allowance? He has not paid any maintenance in this separation period so far except for paying my medical aid.

3. He refuses to return my jewellery that was given to me from him and his family on engagement and nikah. He says it will stay with my daughter because it has to remain in the family. He also refuses to return any clothing or any other items (laptop etc) he purchased for me and that I purchased with my allowance over the 5 years. Is he allowed to refuse returning of my things even though I have taken ownership of theses things.

Q: What is the parental right of the rapist in islam? Does the child belong to him or not?

Q:

1. In the case of children's custody,if the mother does not remarry,who does the children go to?

2. After what age the children can decide with who they would like to stay with?

3. If the mother does not want the children to keep in contact with the father, what should be done?

Q: I have married a woman who has one childern (6 year old girl) with a non believer. The childs father wants to visit his daughter and take her for weekends with him. He is taking her with him to pubs where people are non believers, drinking alcohol and smoking cigarettes. Do I have a right as her stepfather not to allow this visiting, etc.? 

Q: Husband is against niqaab and compells wife to mingle with his family male members. He doesnt want to divorce her but pressuring and humiliating her for changing her to speak to men and fights for the same. Wife is keen on covering herself and wants to know if she can divorce her husband? Will Allah have anger on her if she do so? Their kid is 8 years old, will she get the custody of her kid?