Probating a Will

We have a Will left by our Late father (my brother and I are surviving children in the family, a third child/son passed away in 1992) written by him in June 1996 in New Delhi in which he has passed on all his assets (PPF, savings bank accounts balance, prevailing at the time of writing the Will including a flat that we all lived in) to our mother who is alive. We both (brother and I) are designated by him as executors of his Will. Further he has added (as a final paragraph) that whatever assets are acquired by him after writing of this Will will also belong to our mother as both my brother and I are capable of taking care of ourselves being financially independent. My brother and I are in agreement with father's Will 100%. Our father passed away in Jan 2018 in Thane, Maharashtra without making any other Will to supercede the one written by him in 1996. Our questions are: 1. Can we probate this 1996 written Will in Mumbai or Thane, Maharashtra where we currently reside? 2. Is this probating the Will to be carried out only by High Court in Mumbai or could the district court in Thane do this? 3. Do we need to hire a lawyer to probate the Will or can we apply for this ourselves by approaching the district court or high court (based on your answer to question no.2 above)? 4. How long will this process of 'probating the Will' take? 5. Could we use such a probated Will to sell the current home we live in where the first holder is my Late father, second holder is I (daughter) and nominee is my mother who is 80 years old now. 6. Could this same probated Will be used for getting his PPF funds from a nationalised bank? My mother has been nominated on this PPF account but bank has lost the nomination and asking us now for a probated Will with letter of administration. 7. What will be the court fees charged to probate a Will? 8. If we must hire a lawyer, what will be the fees of the lawyer or is this included in the court fees? 9. Are NOCs from my brother and I needed to sell the home we live in? Both my brother and I are ready to give NOCs to our mother if need be. 10. Will this probated Will overrule any nominations done after the writing of the Will in favour of other than our mother?