How can I get the field settings in a field preprocess hook?
You can fetch the field settings in a preprocess hook by using the following code.

function YOUR_THEME_preprocess_field(&amp;$variables) {
  if($variables['element']['#field_name'] == 'field_event_date') {
    $node = $variables['element']['#object'];
    $field_name = 'field_event_date';
    $instance = field_info_instance('node', $field_name, $node-&gt;type);
    $display = field_get_display($instance, 'default', $node);
    $variables['event_date_formate'] = $display['settings']['format_type'];
  }
}