I would like to have a choice about whether the PhotoView preview window opens when all you want to do is make the final rendering. If the preview window is closed and you select "Final Render", the preview window pops up and hast to start rendering before the Render window opens and starts the fianl render. this to me seems like a waste of processor time. Sure I can hit the Pause button on the preview window, but I have to wait till that button becomes active. When the final render is done the preview window comes out of pause and starts rendering again, which takes up processor power better used to deal with saving the image just created. I don't see the logic of this.
From my understanding the preview window has to open becasue that is the trigger that loads your SW geometry in to the Nexus rendering engine. That's why why the buttons are inactive when the preview window first opens. It needs to load the geometry before you have access to the controls. I believe once the final render window opens the preview window is placed in pause mode so it's not utilizing any resources while the final render window is processing.
I agree the preview and the final render window clutter things up and the final render windows desire to be "on top" of everything is annoying. At one time I believe SW was looking at some way to make the geometry transfer happen more transparently but I'm not sure what if anything they came up with?