How can I display that an event is full on a Drupal View?
One approach would be to use the views_php module to embed a civicrm_api3 call to find out if the event is full, then print the result into the view. E.g.

$event = civicrm_api3('Event', 'getsingle', array('return' =&gt; 'is_full', 'id' =&gt; $row-&gt;id));
if (!empty($event['is_full']) {
  print "Event is full";
}