Premarital relationships

Q: I am studying architecture 3rd year. I am 22 years old. I like a boy who is 3 years younger than me, he is still studying mechanical engineering and is in 2nd year. We both will be completing after 2 years. I spoke about that boy to my mom and she didnt even consider it as his family belongs to a middle class or does not stand with our family status. She strictly rejected it as he is also 3 years younger than me. He is a well mannered person and his character is good as well. I feel that this is more than enough to consider in spouse rather than wealth and family background. I feel that there is no such restriction in Islam when it comes to the age of marrying and moreover our Prophet (sallallahu alaihi wasallam) was 25 years when he got married to Hazrat Khadijah. I said that I will complete my studies and by that time he will be completing his engineering as well and we both looking forward to getting married. My parents are not listening to my wish and are forcing me to marry someone of their choice. Because of all these issues in my home, I am unable to concentrate on my studies. Please help me in resolving this matter. 

Q: Please tell me the method of istakhara for love and arranged marraige and can anyone else do this type of istakhara for me?

Q: I like a girl who is 17 years old and my age is 19 years. We both are classmates. I Would like to marry her. But I am not independent because I am still studying. And she also wants to study. I told her I will approach your guardian as soon as I finish my engineering. The problem is that her guardian is  hurrying for her marrage. And alhamdillah she has very good deen and taqwa. But when I said to her I want to marry, she said my guardian will do my marriage quickly. And alhamdillah we only used to talk. We never met alone. But now what should I do? Shall I say to her guardian that I will marry her after 3 years or as soon as I get independent? What should I do? She is telling me that bring your proposal before I get married. I don't want to show that I did love marriage. Pretend as if you didn't even know me before. Now what should I do?

Q: I'm 27 years old. I'm basically from India and working in this country. My family has arranged a girl for me who is a local Muslim girl born in this country and she's 19 years old. I went to see her few days ago and it seems like both of us are interested in each-other. The families are happy too. Now what's bothering me about her is when I ask her about her past life, she said she has been in a relationships few times. And she did sleep once with a guy. (which I appreciate that she didn't lie or hide) Now after knowing that I'm like almost heartbroken. I also had couple of relationships and I was also engaged in all those haraam acts which I regret now to the core of my heart but I never had sex which I told her. I often watch porn and masturbate. And I only had oral sex. Please help me out. Are we both in a same boat? are we equal sinners? Should I go for her? I have seen she's really sorry about her act. And she's Willing to change.