Nikaah & Marriage Issues

Marrying a married woman

Q: I want to get married to a Christian girl and she is even willing to convert to Islam now. She is not Muslim yet, actually she was with a Muslim boy before and he took her to the mosque to do nikaah as she only did it because that boy wanted her to go to mosque with her and they did as well but as per her she did it because that boy wanted to do nikaah with her according to Islam. The permission of her mother was also not in it.

My question is, was the nikaah valid or not, as she said yes in the mosque in front of the Imaam. If the nikaah is valid then what should I do?

Using one's stepfathers name in the nikaah certificate

Q: I am getting married in July. My mother has done 2 marriages. She is separated and divorced from her first husband long time ago. I was born from her 2nd husband. Not keeping any difference, she and my real biological father kept the name of her first husband as my fathers name.

All my life, my education, identity card everything is made on his name. In my nikaah, my wali agreed to be there but in the nikaah nama (cerficate) the name of my stepfather would come and not my real father. Would my nikaah be valid?

Feeling jealous if husband takes a second wife

Q: Allah created both men and women differently such that a woman does not naturally feel to have more than one spouse at a time.

1. My question is that if it was in the nature of a male to have more than one wife as created by Allah then why are there naturally the feelings of jealousy or insecurities and intolerance that a woman feels about it? My mind and heart both know that Allahs plans are the best and I blindly trust in them but then why I feel annoyed and really bad about the fact of sharing my husband with someone else. I even feel annoyed when my husband teases me about angels of Jannat? Why has Allah put this feeling in us knowing the natural tendency of males? 

2. Though I know that there is nothing wrong in having more than one wife but I still feel uncomfortable and jealous about this fact. I would never be able to stand the fact of my husband marrying someone else. Does that mean that I am not a good believer as my husband constantly keeps saying that if I cannot tolerate the fact of my husband having another wife (suppose) then I am not a good muslimah. Is that so?