Show field's help text on node page
You can get access to help by use field_info_instance function in Your template.php

At the beginning let's assume that You have a field called 'spagetti' created in content type 'Article'. Also,  in this case, mytheme is Your default theme.

First, edit mytheme's template.php file and put into following code:

/**
* Implements template_preprocess_field
*/
function mytheme_preprocess_field(&amp;$variables) {
  $field_name = $variables['element']['#field_name'];
  if($field_name == 'field_spagetti') {
    //Get help ('description' parameter) of field Spagetti
    $instance = field_info_instance('node', $field_name, 'article');
    //Add new parameter to the field
    $variables['element']['#help'] = $instance['description'];
  }
}


Now You can get help value from field array.

For example You may to create template for field spagetti: 
(field--field-spagetti.tpl.php) 
and render field inside:

$field = $variables['element'];

echo $field['#title'];
echo $field['#items'][0]['value'];
echo $field['#help'];