How to achieve triggered redirect after log in so that administration interface will be available on the redirected url?
Try Login Destination , it will redirect you to the destination


  module allows you to customize the destination that a user is
  redirected to after logging in, registering to the site (7.x), using a
  one-time login link or logging out (7.x). 
  
  The destination can be an internal page or an external URL. 
  
  It is possible to specify certain
  conditions like referring pages or user roles and make the destination
  depend upon them. You may use PHP snippets to provide custom
  conditions and destinations. 
  
  It is also possible to keep users on the
  currently visited page after logging in or out.


also take a look at Login Redirect module