I am not sure how to vote at the moment, sorry that doesn't really help you does it
It would be easy to rate the terrain knowing more about the final, but then you would have to give more details away. Just thinking of past experiences where it has not been possible to climb up to a cache.. make a human pyramid, or tie a rope and climb down? Or maybe just use a long reach grab claw? If the latter I probably wouldn't rate a 5* terrain myself, but at the same time it would be using special equipment to get to, and so could be classed as a 5*
As for the first parts, the QR would not be a problem to me. The magic eye would though as I would have to carry a laptop with a program on to reveal the image to me as my eyes are not very magic