Migrate from Drupal To Joomla
I'm assuming this is a new server as well. The first sounds like a PHP issue - some kind of mismatch for the GD extension in php.ini or php-gd rpm package is not even installed. When I say extension I mean PHP extension, nothing to do with CiviCRM other than GD might be used by CiviCRM, but it's usually installed by default. In joomla admin you can go into site system information and see the output from phpinfo to see if it's installed.

The second is probably a mysql trigger/view issue, where you have a different mysql user for your joomla database than the one that created the original civicrm trigger/view. You can either create and use the same mysql user (civicrm@localhost) for your database, or recreate the trigger/views manually. A third option is start again and edit the sql file and edit the part of the trigger/view creation that sets the definer before you import it to the mysql user that you are actually using.