If you have only "NO" as the answer for all the details, then God alone can save you. First of all ask your mother to write to his department intimating his death and request that all his terminal benefits and family pension be settled to her. On the basis of his salary deductions towards Insurance policies, you may may contact the Insurance company and write to them to settle the insurance death claim amount to her as she is the wife of the deceased and in the same letter let she ask the company to provide details of any more insurance policies lying on his name to be settled to her.
This is how you to penetrate into the information circle. From the salary disbursement details you can get the bank account details too, if the salary was disbursed through bank (most of the government organisations disburse the salary through bank only).
Hope with the above clues, you will be able to access and gather complete information about your father. As far as the property details, first of all gather the information of the properties lying at various places, visit the local municipal office or village revenue office, gather the details of the properties lying on his name, then visit the registrar's office, obtain encumbrance certificates on all the properties, find out the encumbrance transaction details,, consult a local lawyer and discuss about the properties which can be retrieved in the capacity of legal heirs to the deceased.
For death certificate you may visit the birth and death registrar's office and obtain the death certificate.First initiate some work, you will find the route automatically after that to all the queries.