Are these REST HTTP response codes correct and what about the Content-Type?

I am writing a controller helper that sets up the correct response headers for my REST controller action. It is inserted below and should be simplified enough for anyone not familiar with Zend Framework to understand what I am doing.

My question is: do these codes match their answers correctly, and in case of "access denied" do I use 401 or 403?

Also, in case of an error response, I understand that I should put the message in the body of the response, but should I set the "Content-Type" to "text / plain"?

<?php

class App_Controller_Helper_RestResponse extends Zend_Controller_Action_Helper_Abstract
{
    public function denied()
    {
        // 403 or 401?
    }

    public function notFound()
    {
        // 404
    }

    public function created()
    {
        // 201
    }

    public function deleted()
    {
        // 204
    }


    public function redirect()
    {
        // 301
        // new url
    }

    public function malformed()
    {
        // 400
    }

    public function gone()
    {
        // 410
    }


}