copy shipping
There is a javascript file called copyShipping.js in the WA_eCart folder.
include the link in your head section like this, (or whatever the correct path is in your case)
<script src="/WA_eCart/Scripts/copyShipping.js" type="text/javascript"></script>
In the table for shipping information, you need to call the script
<tr>
<td><input type="checkbox" name="eC_SameAs" id="eC_SameAs" value="1" onClick="eCart_copyBillingToShipping(this);" /></td>
<td><label for="eC_SameAs">Same as billing address</label></td>
</tr>
If the fields in your address/shipping tables are different from the default, it is quite straightforward to edit the javascript file.