Given a form, how do I find the fields present in them? How do I get the list of fields present in a certain form, I know the form id, I just need the names of the fields present in that form ?
go to your template "template.php for example" or your module, and use

hook_form_alter(&amp;$form, &amp;$form_state, $form_id){
  var_dump($form);exit();
}

and you will get very detailed look at your form