Yes and yes.
Operator, Edit Screen, Screen, Manage Images, Add
To change the image of a screen entity define the image of whatever property it is relative to using scr.SetProperty. All property names are visible in screen edit mode when you click the entity.
scr.SetProperty("SceenEntityName", "Bg Image", "MyImage.png")
or
scr.SetProperty("SceenEntityName", "Image Up", "MyImage.png")