On the homepage I am using the following code to display a few products from a specific category:
{{block type="catalog/product_list" category_id="213" column_count="6" template="catalog/product/list.phtml"}}
Is there a block I can use to also render the category description via a CMS page or block?
There is no built in functionality for this, but you can add a block yourself. Add this in the homepage content:
Now create the file
app/design/frontend/{interface}/{theme}/template/catalog/category/description.phtml
with the following content