Hello,
1) Yes, you can choose another layout in the single product settings http://prntscr.com/w38cqu
2) Go to Theme Options > WooCommerce > Single product builder > Remove the HTML block with the Product Information content from the column of the single product.
3) If you need to create new product you can create it from Products > Add new. Using the Elementor builder you can edit just the main product description but it’s not obligatory. You can use simple HTML tags if you don’t need something extra for the product description.
4) Do you mean you want to use one of the templates created using single product builder?
5) Elementor and WPBakery are page builders. So, you can use it to build the simple page layout, posts content, product description, Static block content (that could be used to create mega-menu, footer layout) etc http://prntscr.com/w38tg7
Regards