I'm currently on H1B but wants to go back to school full-time and convert my status to F1.

1. My sister filed an I-130 for me 6 months ago. A case number and a receipt have been received. Would this be an issue for me to convert my status to F1? No other forms filed (No I-485, etc.), no approval date either.

2. In form I-539, what answer should I put on question 3b: Has an immigrant petition been filed for you or for any other person included in this application?

3. what answer should I put on question 3a: Are you or any other person included on the application, an applicant for an immigrant visa?

4. How long does it take to have an F1 COS approved?

Thanks.