To move the text would require only adding a copy of the tpl_index_categories.php file to your template and moving the following block to where you want it
PHP Code:
<?php
// categories_description
if ($current_categories_description != '') {
?>
<div id="categoryDescription" class="catDescContent"><?php echo $current_categories_description; ?></div>
<?php } // categories_description ?>
Adding another text block is a much bigger deal extending the categories description table and then editing the admin categories.php file allow you to extract, display and update the data you put in the new database column, including possibly hooking up an HTML editor to the new form field. Do you have programming skills?