Nikaah & Marriage Issues

Q:

1. I know that if someone touches his mother with lust, it will break his parents marriage. I want to know if it is permissible for his (the one who touched his mother with lust) children/grandchildren to marry his brother's/sister's children/grandchildren? Are their children/grandchildren allowed to marry each other?

2. Can he (the one who touched his mother with lust) marry his mother's brother's daughter?

3. If the thought comes to mind that a perosn touched his mother with lust during his childhood, but he is in doubt whether he touched or not. What should he do now?

Q: I live in another country due to work. I can afford to look after my family but due to my parents and other family members I am forced to stay abroad and work to save money. My wife is not happy living separate. If I bring my wife here, I'm afraid my parents will get angry on me. What should I do in this situation?

Q: Is it regarded as sinful if a person gets married against his parents wishes?

Q: Can a girl get married without her parents/wali's permission? I read a fatwa that the marriage will be invalid without the girls parents/wali's permission. Please guide.

Q: If a man kisses his wife and during this time the woman thinks of her brother and thinks and feels as if the kisses are being given by her brother, would this affect the woman's nikaah with her husband?

These thoughts are unintentional and she tried fighting the thought and feelings but they kept coming.

Q: Can a husband insert his finger in his wife’s private part to sexually satisfy her?

Q: Is it allowed to see one's spouses private parts while having intercourse? 

Q: If someone touches his brother's wife with lust, will this nullify his brother's marriage? 

Q: If someone touched his own married or unmarried sister with lust, will this nullify his sister's marriage?

If she is unmarried at that time (when the incident happened), will her marriage be valid in future? What is the ruling if she is married at that time (when the incident happened), will this nullify her marriage?

Q: If a man got married and his mum told him that he must not marry again and he's been through hell in his marriage. His mum is late now amd his kids are grown up and working. He found somebody in his life who is going through as much as him. She was an orphan and now he wants to know if he can marry this woman despite what his late mum said. He is only living in the house because of his kids. Can you advise if he can marry and be happy again?