Is it allowed in Islam to do the following: 1) Engagement (betrothal) 2) To feel weak for someone of opposite sex 3) Bankers daughter

Dear Imam, Assalamualaikum. I always had a weakness for my cousin sister who is five years younger than me. I intend to marry her in future. I have never proposed my love to her knowing that it?s not Islamic but sometimes I had talked to her on formal family gatherings and in presence of other cousins and it was about how is her everything (like studies) coming along. Right now, I am pursuing my studies in a foreign land and my weakness for her is also growing as the days passes. Now, I have the following questions: 1) Is it engagement (betrothal) is allowed in Islam? Can I make an engagement (betrothal) by telling it to both of our parents? 2) As I had to call their house in order to talk to my parents (as we don?t have a phone in my house), am I allowed talking to her over the phone? I feel good when I talk to her but I never ask her to talk to me. It's just that sometimes she picks up the phone and I ask about her studies & everything. Am I allowed to do that? 3) Sometimes when I am alone I think of her and contemplate over her. Is this weakness for her and thinking of her a sin in Islam? 4) Her father is working in a bank and that bank deals with interest. So, most probably her fathers earning is not halal according to Islam. So, is it prohibited in Islam to get married to a woman whose father works in a bank and accounts for interest? 5) Sometimes I feel deeply for her. What should I do to control my emotion? Jazakallah, Wassalam Asad