There is and are codes or plugins rather, to do this for you, instead of having to use all that "call tag" stuff in the sidebar.php file..
There is plugins such as "get recent comments", to display the number of posts as well as the "title: of the comment. So it's shown in the sidebar.
Plugin Name: Get Recent Comments
Plugin URI: http://blog.jodies.de/archiv/2004/11/13/recent-comments/
Author: Krischan Jodies
Author URI: http://blog.jodies.de
Description: Display the most recent comments or trackbacks with your own formatting in the sidebar.
a catagory....just use this call tag in your sidebar.php file:
<?php list_cats(0, '', 'name', 'asc', '', 1, 0, 1, 1, 1, 1, 0,'','','','','') ?>
If you want that even specified more, there is plugins available, and for the other..there's a list of links to places for plugins.
I hope the info I gave helps..or maybe I'm not following you're plans just right...I'm not sure.. :/