Hi Sergey Semenov,
The value stored by image_advanced is attachment ID, so when you get them, you will receive an array of integers. (The helper function doesn't work pretty well for group at the moment and I will fix it soon so it can return more info of the image instead of just ID).
In the meantime, please try this code:
<?php $group_value = rwmb_meta( 'rw_mygroup' );
foreach ( $group_value as $group_value )
{
echo '<div>
<div class="image"><img src="' . wp_get_attachment_image_url( $group_value['rw_img'], 'thumbnail' ) . '" /></div>
<div>' . $group_value['rw_textfield1'] . '</div>
<div>' . $group_value['rw_textfield2'] . '</div>
<div>' . $group_value['rw_textfield3'] . '</div>
</div>';
} ?>
You can change the code to use different image size if you want.
