Hi,
For the products in articles, it's the HikaShop content plugin which is used. If you want to change the way the products are displayed with it, you can copy the file plugins/system/hikashopproductinsert/hikashopproductinsert_view.php to templates/YOUR_TEMPLATE/system/hikashopproductinsert/hikashopproductinsert_view.php and modify the copy of that file.
For the products in AcyMailing newsletters, AcyMailing has some documentation to create a custom template:
www.acyba.com/acymailing/161-acymailing-...ashop.html#customize