Questions related to documents for long term Student Visa for France

Hello everyone! I just got my NOC email from Études en France that I can apply for visa. I was even granted an exemption from academic interview and directly got my NOC after few days of paying the Campus France processing fees. I'm still a minor. I'm 17 years old and I'll be turning 18 next year. I was wondering after the documents and proofs to make my application student because I'm hearing a lot about student visa rejection. For the proof of accomodation, I have found it but I have no official rent agreement as I'm going to live at a home with the owner. My owner is so nice! So, she sent a proper email for my visa to indicate that I'll be staying with her and she refused that I don't need to pay her security deposit! I can pay her when I will be in France! So, I'm asking if the email saying that I'll be staying with her is sufficient? And for proof of finance, it's been hard for me to get an education loan, I'm still trying though! My parents can't sponsor my studies because they apparently don't meet the needs and they are already financing my sister's university and accommodation! Could it be possible that my sponsor would be someone else because my teacher, she is ready to sponsor my education and she is ready to give all the documents such as ITR of past 2 years, pay slip, account statement etc... So, can she be my sponsor or it's not allowed! Can someone provide a guidance on my case! I don't want to make any mistake as I can't afford a rejection right now! Please guide me! Thank you so much! Additional Information - I have an Indian passport! Travel history - I had a schegen tourist visa last year for my french immersion program in Paris! It was fully sponsored by the french embassy from flights to accomodation! So, I'm not much aware about the visa procedure and that's it!