Are you referring to descending long hills using engine braking rather than brakes to avoid brake fade?

I can see AWD allowing better engine-braking than FWD in some low-traction situations, but I don't think it would make much difference if trying to stop quickly. I think for modern cars, using engine braking would almost never provide quicker stopping, or more controlled stopping than brakes alone.

Regarding three pedals, you could downshift in an two-pedal automatic too couldn't you?