Hi,
You'll need to modify the code for the ad block. If you look in the _bannerRightContent.inc.php file you'll see the code for the right-hand side. You should be able to add you ad code here. Failing that, we can provide a quote to do the work for you.
Re. the download issue - what do your server logs say? Have you tried setting the permissions of this file, it looks like your web server is blocking access to it.
Regards,
Adam.