"What is the standard print size and viewing distance and how does changing that change the result"
The standard print used by DxO is 12x8 - or about 8 mp. It really does not matter what the size is - just that you standardize the image so you can compare different sensors. In the case of a 36mp image being downsized to 8 mp, you have 4 pixels being converted to 1. That causes a lot of noise to disappear. DxO has measured the amount. But more importantly, this approach provides the ability to compare an image as it woudl be printed and viewed.
"compared to the human eye, how much dynamic range can the camera see and record."
This is the magic question, because it varies a great deal by the ISO setting. At low ISO levels the camera records a great deal of the dynamic range, but at higher ISO levels that still have little noise, the dynamic range is much less. Take a look at the DxO measurement data to see the graphs of how it changes. Bill has similar graphs. There is a very big dropoff in dynamic range at high ISO levels.
I agree that noise is a separate issue. It seems to be all we talk about with the latest cameras is noise levels, but that is just one of the three major areas of image quality. In addition to noise, dynamic range and color range are important. The latest camera offer vast improvement in dynamic range and color range - something that gets overlooked and is probably more important for 90% of your images. But if you are shooting at high ISO levels, you are not maximizing dynamic range or color range and unknowingly might be giving up something important.