Forcing a girl to get married

Q: If the parents have done everything they could for their children, for example, my father has scarficed a lot for his children, he gave us education. We are 6 sisters and 3 brothes. All my brothers Alhamdulillah are engineers and two elder sisters are married and two are Alhamdulillah doctors.

My question is that one of my sisters, who is a doctor is being forced to marry our cousin who is my father's nephew. Years ago the relation was tied and my sister had no clue about it, she got to know later when it was made official. After her graduation my parents, even my brothers and two elder sisters who are married are forcing her to marry the cousin. All these years she was highly depressed over it and would cry in sajood. Meanwhile our parents and our elder siblings have told us that we should marry whoever our parents want us to because they've sacrificed a lot for us and that our father gave us education in the society where girls aren't supposed to get out and study. And in our society we do not marry out of the cast. So we have no option. We have to marry our cousins. It doesn't matter if they're educated or not.

Basically my question is that are we disobeying our parents or taking their sacrifices as for granted if we aren't willing to marry who they want us to get marry? My sister is really depressed. All these years she'd cry but now when the days have come close she has agreed to marry because she has been pressurised if she doesn't get married to whoever her father wants, it'd hurt her parent's feelings plus she has no choice rather than the cousin cause her age will pass by and none will marry her because as I mentioned above we are not supposed to get married out of our cast according to our society.

Qadha-e-umri

Q: I'm a hanafi by maslakh. My question is about qaza e umri. Is qaza e umri to be offered or not. If yes please give the daleel in the light of Qur'an and Hadith. Few of my friends confused me as I don't have the daleel.

Reciting three quls and Ayatul Kursi before sleeping

Q: My sister is 5 years old and she is a normal girl. At night when she sleeps she wakes up at 2 am and starts crying and she is repeatedly saying Allahu Akbar bismillahir rahmanir rahim and after 10 to 15 minutes she gets normal again and goes back to sleep being exhausted and once she gets up she dont remember what all happend. This is happening with her from past one month.

Becoming a singer

Q: I want to ask that is becoming a singer Haram? Let's suppose someone is becoming a Singer so that he/she can have millions/billions of dollars from which he/she can remove poorness from this world and help the needy. Is it haram to listen to Music?