Product Querying
wcgetproducts and WCProductQuery provide a standard way of retrieving products that is safe to use and will not break due to database changes in future WooCommerce versions. Building custom WPQueries or database queries is likely to break your code in future versions of WooCommerce as data moves towards custom tables for better performance. This is the best-practices way for plugin and theme developers to retrieve multiple products. wcgetproducts and WCProductQuery are similar to WordPress getposts and WPQuery. Just like those, you pass in an array of arguments defining the criteria for the search.
Custom attributes in menus
Attributes that can be used for the layered nav are a custom taxonomy, which means you can display them in menus, or display products by attributes. This requires some work on your part, and archives must be enabled.