1. The legal heirship certificate will not be applicable to the movable properties of the deceased.
A succession certificate or letter of administration by an order of court would be the perfect document to claim the amount to the credit of the deceased by the successors in interest.
2. This is company's discretion based on its own policy for disbursement of death claim to the successors of the deceased.
You can ask the company itself directly ab out it becasue ther is no law to force the company to accept your this proposal.
3 Any person entitled to any legal character or to any right as to any property, may institute a suit against any person denying, or interested in denying, his title to such character or right, and the Court may in its discretion make therein a declaration that he is so entitled, and the plaintiff need not in such suit ask for any relief.
Provided that no Court shall make any declaration where the plaintiff, being able to seek further relief than a mere declaration of title, omits to do so.
4. If there are no respondents, then the succession OP should be decided within the span of three months, depending on the burden of cases in the concerned court.
The lawyer fee may be enquired from the lawyer likely to engage, there is an additional fee called stamp duty at the rate of 3% to the value of the property/shares.