This is my response to you:
1. Do I need to sign an ‘Agreement of Sale’ under HRERA or BBA is sufficient? I have sent multiple reminders to builder asking them if this Agreement of Sale needs to be done or any other formality to be compliant with HRERA, but no response.
Answer: For now BBA is enough. After the builder procures the CC and OC then only you can execute the 'Agreement for Sale';
2. Since project is under delay, it cannot be completed by Feb’2020. Is there a way I can get full refund with interest now or do I need to wait till Feb 2020? Is BBA sufficient in RERA authority to seek refund?
Answer: Since it is registered with RERA, then full refund is not possible. The builder will forfeit certain percentage from it. But if according to the BBA the builder has stated that full refund will be made then you can approach him likewise;
3. There are some doubts on financial condition of builder too; can this be a basis to seek refund clubbed with point#2 under RERA?
Answer: The financial condition of builder is not for your to ascertain. You must check your allotment letter and the BBA if there is clause for refund, if yes, then what is it?