a: for the index page menu, in the CSSMenuWriter/cssmw_home/menu.css change the width in the ul#cssmw_home > li > a, ul#cssmw_home > li > a:link selector.
for the other pages, in the CSSMenuWriter/cssmw_content/menu.css, change the width for the ul#cssmw_content > li > a, ul#cssmw_content > li > a:link selector.
b: To change the widths individually, edit the CSSMenuWriter/cssmw_home/menu.php and CSSMenuWriter/cssmw_content/menu.php files, add an inline style for the width to the anchor tags, for example:
<li><a href="<?php echo($assumedRoot); ?>index.php" style="width:80px;">Home Page</a></li>