1) Since this is a routing issue, show what you have for the route in the module.config.php file. You might not have the "param" constraint configured properly in your config if I had to guess.
It should look something like this:
'confirm' => array(
'type' => 'segment',
'options' => array(
'route' => '/controller_name/confirm[/][:param][/]',
'constraints' => array(
'param' => '[0-9]*'
),
'defaults' => array(
'__NAMESPACE__' => 'your_namespace', // ex. Application\Controller
'action' => 'confirm', // or whatever action you're calling
'controller' => 'controller_name' // ex.
),
),
),