variable_get/set not working right
In your code where you are setting the value move the last line above variable_set() function

Change this code:

 $staff_action = $_GET['staff_action'];
$first_name = $_GET['first_name'];
variable_set('first_name', $first_name);
$last_name = $_GET['last_name'];
variable_set('last_name', $last_name);
$email = $_GET['email'];
variable_set('email', $email);
drupal_set_message($email . " in first function");


To this:

 $staff_action = $_GET['staff_action'];
$first_name = $_GET['first_name'];
variable_set('first_name', $first_name);
$last_name = $_GET['last_name'];
variable_set('last_name', $last_name);
$email = $_GET['email'];
drupal_set_message($email . " in first function");
variable_set('email', $email);


Then it should work.