Super-Simple WordPress ajax post-popup with jQuery and Reveal plugin

ajax.php

<?php
/**
 *   Template Name: ajax
 */
?>
<?php
    $post = get_post($_GET['id']);
?>
<?php if ($post) : ?>
	<?php setup_postdata($post); ?>
	<div class="something">
		<h2 class="title"><?php the_title(); ?></h2>
		<div class="content">
			<?php the_content(); ?>
		</div>
	</div>
<?php endif; ?>

popup.js

// We are using Wordpress' jQuery (in no-conflict mode)
// 	and the reveal plugin (http://zurb.com/playground/reveal-modal-plugin)

jQuery(document).on('ready', function () {
    
    // Click on element with 'popup' class 
    jQuery('.popup').on('click', function () {

        // Save ID in simple var
        var id = jQuery(this)
            .attr('rel');
        
        // Hide entire div and load in it the Post ID
	jQuery('<div id="wp-popup"></div>')
            .hide()
            .appendTo('body')
            // Substitute 'ajax' with your wordpress template name,
            //      and 'EXAMPLE.com' with your real URL
            .load('http://www.EXAMPLE.com/ajax/?id=' + id)
            // Modal Window
            .reveal({
                // Optional parameters
                animation: 'fadeAndPop',                   // fade, fadeAndPop, none
                animationspeed: 300,                       // how fast animations are
                closeonbackgroundclick: true,              // if you click background will modal close?
                dismissmodalclass: 'close-reveal-modal'    // the class of a button or element that will close an open modal
            });
            
        return false;
        
        });
});

simple-button.html

Clicca <a href="#" rel="INSERISCI_POST_ID" class="popup">qui</a> per aprire il popup con l'articolo.
Click <a href="#" rel="INSERT_POST_ID" class="popup">here</a> to open post-popup.

i should use that ajax.php as a template in my pages ?

this wont work when user is logged out, any fix for that?