Include additional customer information

In the Pdf Customiser template file, you can use the following snippet to display additional customer information. Tailor this to meet your requirements - the example shown below will add the customer email address to the pdf. 

<?php $order = $this->getPdfHelper()->getOrder()?>
<?php if($order->getCustomerId()):?>
    <?php $customer = Mage::getModel('customer/customer')->load($order->getCustomerId())?>
    <?php echo $customer->getEmail()?>
<?php endif; ?>