On Magento I have tried
Mage::log ($order);
I suppose to get the array printed on my
var/log/system.log
But instead the website does not load again, after few min it comes as timed out.
try this
Mage::log($order->toArray());
Try that: Zend_Debug::dump($your_variable);
And this is one of the best posts about that in my opinion: MAGENTO DEBUGGING HINTS
Mage::log(array_keys($order->getData())). This should print you a simple array with keys of the order model instance. Then pick your key and just log thisMage::log($order->getData($key)).