Alright, I understand that the plugin is programmed only for coppermine in mind and that you don't have time to support different versions of it. However I'm not a programmer so I don't know how to write the code for the bridge file (which would be joomla.inc.php file I think from Mehdi). Those query's you talking about, I've found these in your code, are they all? If they are I 'll try to ask Mehdi about it...
photo_shop_admin.php
$result = cpg_db_query("SELECT s.*, u.user_name, u.user_email FROM {$CONFIG['TABLE_SHOP']} AS s LEFT JOIN {$CONFIG['TABLE_USERS']} as u ON u.user_id = s.uid WHERE aktive=".$box." AND cd=1 ORDER BY ". $sort_codes[$sort] ." LIMIT $lower_limit, $orders_per_page;");
$result = cpg_db_query("SELECT s.*, u.user_name, u.user_email FROM {$CONFIG['TABLE_SHOP']} AS s LEFT JOIN {$CONFIG['TABLE_USERS']} as u ON u.user_id = s.uid WHERE oid=".$oid." AND cd=1 LIMIT 1;");
photo_shop_register.php
$sql = "SELECT user_id " . "FROM {$CONFIG['TABLE_USERS']} " . "WHERE user_name = '" . addslashes($user_name) . "'";
$sql = "SELECT user_id " . "FROM {$CONFIG['TABLE_USERS']} " . "WHERE user_email = '" . addslashes($email) . "'";
// Are you sure I'll need those below?
$sql = "INSERT INTO {$CONFIG['TABLE_USERS']} ".
"(user_regdate, user_active, user_actkey, user_name, user_password, user_email, user_profile1, user_profile2, user_profile3, user_profile4, user_profile5, user_profile6) ".
"VALUES (NOW(), '$active', '$act_key', '" . addslashes($user_name) . "', '" . addslashes($encpassword) . "', '" . addslashes($email) . "', '$profile1', '$profile2', '$profile3', '$profile4', '$profile5', '$profile6')";
$sql = "SELECT user_active user_active, user_email, user_name, user_password " . "FROM {$CONFIG['TABLE_USERS']} " . "WHERE user_actkey = '$act_key' " . "LIMIT 1";
$sql = "UPDATE {$CONFIG['TABLE_USERS']} " . "SET user_active = 'YES' " . "WHERE user_actkey = '$act_key' " . "LIMIT 1";