1) Instead of [[ category ]] use [[ $entry.category.0 ]] That will give you the (internal) name, which is safe for filename usage, and not the display name.
2) For the category list I would have used:
- Code: Select all
<ul id="category_list">
[[ category_list format='<li class="%name%"><a href="%url%">%display%</a></li>' ignore='notused' ]]
</ul>
and the in a CSS file assign the images to "ul#category_list li.categoryname".