An uncaught Exception was encountered

1. application\config\database.php
 'database' => 'database_name'

2. Depends on how your CMS are coded. Menus etc are generally depending on $config['base_url'] set in application\config\config.php. But if your application includes WYSIWYG, they need to be edited that way. Or search and replace in database.

3. Maybe, hard to tell without any code.

4. You got Profiler turned on:
https://www.codeigniter.com/userguide3/g...iling.html