All the PDFs we used to have are now converted and have been placed into the knowledge base area.
How would this help me on building a site? would it allow me to hide a background on 1 page and use another on a different page, or use a background on 1 page and none on another?
The 2 background options that each section has (area1 and area2) won't allow you to show/hide page specific. Its one DIV, area1 with another DIV inside it, area2. Most times you only need to place 1 image on a background of a section but sometimes you may need to. In the case you want to have a gradient separate from the image. You could place the image in area1 and the transparent gradient in area2 thus your site shows a gradient over the image and it just looks like one picture. Maybe you want a logo or some image that is a full width/height of a section. You could place this in area2 again and another image below it. With Vertex we tried to think through as many options/features/possibilities and allow for them, so this is just an example where you can place a background image on top of another.
no idea.. is there a way to hide a background for a menu item if I want to use a module position in a menu item that has a background published on the front page already?
I'm not sure I follow 100% on this but you can't hide backgrounds unless you unpublish all the modules in a particular row. Once all the modules are not published to that row on a specific page that obviously the row won't show along with the background that was on it.