in the WA_Universal_Email\Templates\contactus.php file change line 13 - 14:
<strong><?php echo(str_replace("_"," ",$pkey)); ?>: </strong>
<?php echo(str_replace("\n","<BR />",$pval)); ?>
to:
<?php if($pval != "") { ?><strong><?php echo(str_replace("_"," ",$pkey)); ?>: </strong>
<?php echo(str_replace("\n","<BR />",$pval)); ?><?php } ?>
To change the value that is displayed in the email, you just need to change the Checked value for the check boxes:
<input name="checkbox" type="checkbox" id="checkbox" value="ON">