Nikaah & Marriage Issues

Hurmat-e-musaaharah becoming established through looking at the private part of a woman

Q:

1. What is the private part of a female that by looking at it hurmat can take place?

2. If a woman is wearing full clothes in a picture or in real life and someone unintentionally looks at her chest and lowers his gaze, and her cleavage is slightly shown, like a very small part of her cleavage, just few milimeters. Does this form part of a females body where hurmat can take place? Even if the person has no lust for her?

3. If a person has shaken hands with an old lady and he is 100 percent sure that there was no desire or lust at that time but he is having waswasa. Should he pay attention or disregard this thought?

Asking for one's mahr after giving it to one's husband

Q: 12 years ago I got married. My haq mehr was decided to be paid later. There is a fight between me and my husband related to the amount he spent on our honeymoon. To make the things simpler, I said that you can keep my mehr amount to compensate your expenses. Later on, I spent 12 years of my life in an abusive marriage. I never demanded this amount again. We have 3 children.

Now, he divorced me and married another women. Can I demand my haq mehr amount now as I have once forgiven it or given it to him? I also need it for my children. He has also not returned my jewellery that was given to me at the time of our wedding as a gift. Can I demand my haq mehr now, as I have once forgiven it or given it to him? 

Will hurmat-e-musaaharah become established through shaking hands with an old woman?

Q: If a person has a stomach issue, when he eats spicy or high calories foods, he gets some white drops coming out from his penis in a normal state without any errection or lust. Now if he shakes hands with an old woman without any lust or erection, will this be hurmat?

Please note that there is no lust or erection for this old lady. The person has a stomach heat problem because of which he gets these drops when he eats spicy food.

Marrying a chaste woman after committing zina

Q: I got into a debate with a person who has quoted from the Quraan about the topic on fornication. She stated that according to her understanding of the verses, a fornicator, even if they have repented cannot marry a pure person and if they do then the nikkah will not be valid. I debated that Allah Ta'ala forgives the sincere repenter so how can they be punished if they go on to marry a virgin etc. Please shed some light, was I right in my reply?