Is there any way we can assign a shortcode to already created widget and later use that
shortcode in our specific posts and pages to show that widget instead of trivial method of
showing widgets in sidebar ? I googled about this stuff didn't find anything relative.
Any suggestion would be welcome!
Yes, You can call widget in Post/Page using shortcode. Follow this link to establish a system like that. http://digwp.com/2010/04/call-widget-with-shortcode/