Category misses options for product layout and parent

Hi,

"manufacturer" is not a normal category. It's the main category where you're supposed to create your brands. That way, when you edit a product, you can select the brand of the product for the "brand" setting.
This main category, and it's sub elements (which are brands) are not supposed to be selectable in the "categories" setting of the products and the product page layout being based on categories and not brands, it's normal that you can't select one for brands or the main "manufacturer" element. Also, you can't change the parent category of the main elements. That's done on purpose so that you don't mess with the main structure of the category tree as it's used to store at the same time the product categories (under the "product categories" main element), the brands (under the "manufacturer" main element) and the tax categories.
So you're not supposed to be able to link products to the "manufacturer" element as a category. Also, discounts and coupons are supposed to be linked to categories, not brands, so you shouldn't even be able to select it there.