In Drupal 7, you can use taxonomy-term.tpl.php to override taxonomy pages.
Inside the taxonomy-term.tpl.php page, you can use
<?php print $term->field_NAME['und']['value'];?>to print out the content of any fields attached to the taxonomy term. (*)
However, how do you get to the list of nodes that is displayed on the taxonomy page?
There doesn't seem to be anything in the taxonomy-term.tpl.php file to indicate how to theme the nodes that are displayed on the term page.
I know you can use Views to over ride the page. However, Views does not let you display nodes tagged with a term and fields that are attached to the term in a single View.
(*) I know you are not supposed to use UND. However, the correct method for access node based fields does not seem to work with taxonomy based fields.