How can I add a custom configuration area to a node edit form just beneath the Authoring Information & Publishing Options section?
You can use hook_form_FORM_ID_alter(). Example below:
function my_module_form_node_form_alter(&$form, $form_state) {
// if you are targeting a specific content type then
// you can access the type:
$type = $form['#node']->type;
// Then
if ($type == 'my_content_type') {
// use a contact settings for the sake of this example
$form['contact'] = array(
'#type' => 'fieldset',
'#title' => t('Contact settings'),
'#weight' => 100,
'#collapsible' => TRUE,
'#collapsed' => FALSE,
);
// add simple checkbox to the field set
$form['contact']['approve'] = array(
'#type' =>'checkbox',
'#title' => t('Contact me'),
);
}
}
Now For storing the data I encourage you to see the examples project; it has many code examples with lots of documentation. Also, Check the Form API for more information on different types of form elements. Hope this helps.