1. The share of the deceased share holder shall devolve on his own legal heirs which comprises his widow and children, hence they have to execute the sale deed in respect of their legitimate share in the share of property that belonged tothe deceased shareholder, nomination ion the society will not confer marketable title on them to sell this property. Better to obtain a legal heirship certificate.
2. There is no time factor, if everything is alright, you may go ahead right away.
3. First of all purchase the property by a registered sale deed duly executed by the vendors afterwards you can enter into the agreements as other members of the society, with the developer complying with lot of formalities therein.
3. You will be informed about it based on the prevailing circumstances
4. If you want to buy the property before redevelopment then it is a transaction between you and the vendors only.
5. Losing of relevant link documents is a serious lapse, there can be no excuse for this, you may ask him to produce the certified registration copies of the lost documents following the proper procedures of law in this regard, besides indemnifying you for the same against all future legal issues and losses therein.