It depends on the size of the flat. We need more details in terms of locality, amentiy, flat carpet area to determine the right price. Is this in a building with or without OC?
Society can only check whether the Developer's past or current projects were/are registered with RERA. RERA registrations are project specific not Developer specific.
We need more details to answer this question. Is the builder demading increased base cost or is it to cover new additional taxes that have been introduced by the government?
Generally these spots are noticed during monsoon because of high level of moisture and most likely spread thru ceiling fans. The simple solution is to keep blades of ceiling fans dry and dust free and keep windows open as much as possible for natural ventilation.
A person of Indian origin is entitled to hold property in India however, the repatriation of funds on sale of a property in India to abroad would depend on the relevant foreign exchange regulations in that regard.
Depnding on the religion you follow, if you are Hindu, then you, your sister and mother will all be entitled to the estate of your deceased father and will have equal shares in his estate.