How to pre-populate a text field when creating a new node?
instead of $form['field_FIELD_NAME']['und']['#default_value'] you should use 
$form['field_FIELD_NAME'][LANGUAGE_NONE][0]['value']['#default_value']
try something like:

$form['field_manager_name'][LANGUAGE_NONE][0]['value']['#default_value'] = 'hello world';
$form['field_manager_email_address'][LANGUAGE_NONE][0]['email']['#default_value'] = "nobody@yahoo.com";