juani

try this:

RedirectMatch 301 ^/author/(.+)$ http://www.yourblog.com/$1

I use it in my site http:futborama.com

yes, open te common.php file in line ~194 and change this:
$fbusername = 'fb'.$fbuid;

for this:

$counter = 1;
  $fbusername = str_replace( ' ', '', $userinfo['name'] );
  if (username_exists($fbusername)) {
	do
        {
            $username = $fbusername;
            $counter++;
            $username = $username . $counter;
        } while ( username_exists( $username ) );
    }
    else
    {
        $username = $fbusername;
    }
    $username = strtolower( sanitize_user($username) );

  $userdata = fbc_userinfo_to_wp_user($userinfo);
  $userdata['user_pass'] = wp_generate_password();
  $userdata['user_login'] = $username; //login with new nice username
  $userdata['user_nicename']= $username; //show name with new nice username

you can see in action in my video soccer site http//futborama.com

You might look this function wp_set_post_terms( $post_ID, $tags, $taxonomy, $append ) in the codex http://codex.wordpress.org/Function_Reference/wp_set_post_terms.
I use it in a form of my classifield site 😉