** HELP WITH DOWNLOADS **

Sorry to correct you but there is an easier way, it's called the Content-Disposition header and I personally (please don't get this wrong) don't understand why you should use an iFrame at all.

You can simply use a PHP script for that purpose.
Here is one I quickly created from scratch based on a method I'm using on my websites.

If you save it as e.g. dl.php a link would look like this:
<a href="dl.php?file=info.zip">Download</a>

The code assumes that the file to be downloaded is located in the same directory as the PHP file, if it's in a different directory you need to modifiy the $path variable accordingly.

<?php

// Using basename() to prevent downloading arbitrary content from the server
$file = basename($_GET['file']);
$path = dirname(__FILE__).'/'.$file;

// Check if the file exists
if (!file_exists($path) || !is_readable($path)) {
header("HTTP/1.0 404 Not Found");
die("<h1>404 File not found.</h1>");
}

// Content-type, PDF e.g. would use application/pdf
header("Content-Type: application/octet-stream");

// This tells the browser to download the file (attachment)
header("Content-Disposition: attachment; filename=".$file);

// This tells the browser that the content shouldn't be cached
header('Expires: ' . gmdate('D, d M Y H:i:s', gmmktime() -3600) . ' GMT');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');

// Content-Length
header("Content-Length: " . filesize($path));

// Open the file to be downloaded and send it to the user
$fp = fopen($path, "r");
fpassthru($fp);

?>

Hope this helps