If you are looking for a plugin to manage image gallery, you can use attachments
plugin,
http://wordpress.org/plugins/attachments/
It keeps the gallery separate and does not put the image gallery shortcodes in post content, thus providing you with full hold over image display in your post/page/custom post. You can also change the order of your images by just drag-n-drop
here is a sample code of how to retrieve your gallery images,
<?php $attachments = new Attachments( 'attachments' ); /* pass the instance name */ ?>
<?php if( $attachments->exist() ) : ?>
<h3>Attachments</h3>
<p>Total Attachments: <?php echo $attachments->total(); ?></p>
<ul>
<?php while( $attachments->get() ) : ?>
<li>
ID: <?php echo $attachments->id(); ?><br />
Type: <?php echo $attachments->type(); ?><br />
Subtype: <?php echo $attachments->subtype(); ?><br />
URL: <?php echo $attachments->url(); ?><br />
Image: <?php echo $attachments->image( 'thumbnail' ); ?><br />
Source: <?php echo $attachments->src( 'full' ); ?><br />
Size: <?php echo $attachments->filesize(); ?><br />
Title Field: <?php echo $attachments->field( 'title' ); ?><br />
Caption Field: <?php echo $attachments->field( 'caption' ); ?>
</li>
<?php endwhile; ?>
</ul>
<?php endif; ?>