GPU on top is working very well for CPU & PSU in CL530..that's why..Yes, everything will be steel except from the mask which we be aluminum. I had to do this to keep it light enough not to get into next price tier for shipping (over 5kg).
It doesn't have official support for inverted orientation, you could stick some feet to the top panel and invert it, but I don't recommend it, since I am sure that it will actually have worse cpu and psu temps. And some of the gpu exhaust could still get to cpu because of active airflow. You can always try it out
It mainly depends where is located your case (right or left from monitor).