Transfer of Property from dead father

My father died 2 years before and my mother died 9 yrs ago and my late father has two sons and no daughters, my elder brother died 9 years ago. My late father has a property in bangalore a BDA site. Since my father did not made any will and me and my sister in law have decided to transfer property jointly b/w myself and sister in law. My question is

1.what are the documents needed to transfer property

2. Whether we have to pay stamp fee for transferring property? If so what is the stamp fee amount in bangalore for a property worth 3.5 crore

3. Whether succession certificate is needed? Or family tree certificate is sufficient