Retrieving users

This is a multi-part question

1. How do I retrieve a list of all the users on a site (not an MU site)? I'm using WP 3.1.2 and the recommended method I'm using is this:
//available since WP 3.1
$wp_user_search = new WP_User_Query( array( 'role' => 'author' ) );
$users = $wp_user_search->get_results();
The problem is I want all users and if I don't pass any argument to WP_User_Query then a NULL is returned. So is there a simple way to get all users?

2. Once I have the $user array and I use a var_dump, I see most of the items I need to use except one of them. It doesn't seem that WP_User_Query returns the author description. Is there a way to retrieve the author description with the WP_User_Query?