Question – My USC aunt filed a GC application for my mother

My USC aunt filed a GC application for my mother living in Bangladesh. The application was received in 2009 and today, in July 2018, my mother, father, and 17-year-old brother got asked to take the interview on 1 Aug, 2018. Although I am single and 22-year-old now, I was under the impression that because I was below 21 when filed, I would still be called for the interview. I am in my senior year of college in the U.S. with an F-1 visa and am currently residing in Massachusetts. I came to this country 3 years ago to get my bachelors degree. Is it possible that I am “not required” to attend the interview but “may attend” the interview? I don’t know if its something technical because I have heard some family members being denied the GC while others get granted the GC ON SPOT during the interview but I don’t understand why I would not even be called for the interview especially because the application fee was paid for online by my aunt for all 4 of us. I was studying in Boston while the other 3 people in my family are back home in Bangladesh. We all have Bangladeshi passports and only I have a B1/B2 that will expire in 2019 and my F-1 will expire in 2020 unless I renew it when I get admission for grad school in the U.S.

Email excerpt (containing PDF for interview letter) from U.S. Embassy was as follows:
Your immigrant visa interview is at the U.S. Embassy or Consulate in DHAKA, BANGLADESH on August 1, 2018 at 07:30 am. The following applicants should attend this interview: “Mother’s name, Father’s name, 17 yr old brother’s name”

This is great news BUT my name was not mentioned in the above statement. What does this mean? Can I still go or at least apply to be part of the interview? The interview is in 3 weeks and I have to go home plus get my medical check-up done so I am panicking what to do as the other members of my family still have to carry on and prepare for the interview.

In the worst case scenario that my mother and everyone except for me does receive the GC, can my mother apply for my GC and how long might that take to process?

Question – Hi I am an international student in the MS program

Hi, I am an international student in the MS program and applying for unpaid work.
Do I need to apply for the OPT that same as other international students who have a paid job?
What should my employer must do for me to have me as an volunteer at their practice?