MarketPress Brand Directory

Hi there! Is there a place in this version of Marketpress i can insert Brands? I tried to crate this Brand directory as Taxonomies using CustomPress but is just another tab in my Dashboard without integration with Products. If I could add Brands in the "Store URL slug" would be perfect, some way my items show like brand/product-category/product-name.

Other thing, my users need to shop by size, the only option I could do was adding size to product's tag and than in a widget all sizes using the tag url, but this is very slow! I there how to add a size color and brand fields when I create a new product?