1. If it is blood relative your father can with help of unregistered POA sale if he is the agent and also if the relative is still alive. Though content and time of POA has to be seen.
2. See for registered POA you can engage an advocate to draft and help you register the POA. Further stamp duty as per state has to be paid along that adhaar card and presence of both parties before registrar is required.
3. Yes you can take POA from NOIDA same shall be valid in bihar.
4. Yes there is a way you can file an application based on health of your relative and registrar under provision of.registration act can register at home. A medical certificate of doctor is required for.same.
5. It has to be from local jurisdiction only.