1. No - it's just a plain blue sky type of set up.
2. Often you'd use a 'backplate' image with the domelight. You can use the domelight image itself as a background, but because you would typically be viewing just a small part of the domelight 'sphere' - depending on camera focal length - you'll need a very high domelight resolution to give you reasonable 'image resolution' in your render. Also - because the domelight is calculated at 'infinity' you can't move it up or down - it would have no effect. You can rotate it of course.
So, typically you'd use a 'backplate' image - see settings in the domelight, which just covers the camera view, to be your rendered background image.