Creating a Product based on Codeigniter

[eluser]Unknown[/eluser]
If were to make a Word Press-like product using Codeigniter, could I legally sell it?

Beyond that, even I didn't sell it, and built/released the product for free, I see myself making changes to the source. What's the right way to comment myself as author that made alterations?

I've been programming for a while, but I've just recently become concerned with having the right level of commenting and adhering to some type standard while doing so. It looks like Codeigniter is using Perl Standards. (http://pear.php.net/manual/en/standards.header.php). So if I add myself would it look like this?

Code:

/**
* CodeIgniter
*
* An open source application development framework for PHP 5.1.6 or newer.
* Alterations made by Dennis Mars for the FooBar project (2011).
*
* @package        CodeIgniter
* @author           ExpressionEngine Dev Team
* @author           Dennis Mars <[email protected]>
* @copyright      Copyright (c) 2008 - 2011, EllisLab, Inc.
* @license           http://ellislab.com/codeigniter/user-guide/license.html
* @link                http://codeigniter.com
* @since              Version 1.0
* @filesource
*/

[eluser]Basketcasesoftware[/eluser]
It's part of the license agreement that you can sell derivative works. Just make sure you include original CI source and the license document with it.