This has caused many issues before. I don't know who keep recommending this, but they must not be aware of some of these issues with it. The only advantage to that method is you can have some custom text on the products page that can be edited via the standard edit panels. The way I'd suggest doing this is to have a template file for your custom taxonomy, and have it display the taxonomy tag description for your additional information.
I'm going 2 steps back and starting over again. I would like to use your solution, but I did not get point completely.
Here is the code for my custom post type:
register_post_type( 'demaweb_product',
array(
'labels' => array(
'name' => __( 'Products' ),
'singular_name' => __( 'Product' ),
),
'public' => true,
'rewrite' => array('slug' => 'products'),
'supports' => array('title','editor','excerpt','page-attributes','revisions'),
)
);
I found this example of how to create a custom taxonomy:
http://codex.wordpress.org/Function_Reference/register_taxonomy#Example
But how should I define the taxonomy? Should I eg. create this hierachical taxonomy called "product":
register_taxonomy('product',array('demaweb_product'), array(
'hierarchical' => true,
'show_ui' => true,
'query_var' => true,
'rewrite' => array( 'slug' => 'products' ),
));
I then guess, that the URL /products/ would act like the normal /category/ URL - but now showing a archive for the taxonomy? But how can I then create a custom file in my theme defining the layout of my /products/ page? Right now I got the 404-page.