1) Admin notices – not so fast. I’m working on the answer currently.

2) You may turn ON this option ‘Activate “Create” capability for posts/pages/custom post types”. ‘create_posts’, ‘create_pages’, ‘create_products’ capabilities will be appear in the User Role Editor. Add them to the roles which should add posts, pages, products and other registered custom post types. Role without ‘create_products’ capability will can not add new product – just edit the existing one.