Ok, so in the example, when I pick a layout to go to, go to a loading layout and use the "load layout images" action?
Unfortunately, no. You can only preload images to use in the current layout. As soon as you switch to another layout, the memory will be cleared, and then all images from the new layout will be re-loaded again..
I have seen many games where there is an option for quality (usually high, medium, or low).
There is a GFX plugin which allows you to change graphics quality. I only tested the included demo project, but it looks impressive.
I believe in most games "quality" means different things. For example, on low quality you may disable some effects, remove some particles or decrease their spray rate, replace background images with lower resolution versions etc.