Hi @tarun_kumar,
About the search bar, may I ask why you are unable to simply use the filter bar itself? It is also capable of doing text searches. Providing two search/filter bars on the same page might be a confusing UX for the user.
To extract the date range filter applied to the dashboard, look into using the timefilter Angular service provided by Kibana. Once injected, you can call its getBounds method to get an object with min and max properties. You can see an example usage here.