How to get Images included in Post

You can use get_posts() (Codex ref for getting Post attachments).

<?php
$args = array( 
    'post_type' => 'attachment', 
    'post_mime_type' => 'image',
    'numberposts' => -1, 
    'post_status' => null, 
    'post_parent' => $post->ID 
); 
$attached_images = get_posts( $args );
?>