Hi,
An easy way to display the manufacturer products is to use the manufacturers as product categories.
Create a new branch of categories under the Product > Category menu, and add all your brands here. Then in the product edition page, add the desired brand in the category part (one product, many categories).
Finally create a menu/module listing the categories based on the brand parent category, and associate a product listing module to that menu, this way, you will have the products per brands displayed.