Don't forget that in the evolution of primates, there were a large number of species in Europe and the northern parts of Asia for much of the time we primates have been on the planet. Large size and cold tolerance go hand in hand. Simple extrapolation of great ape strength could well account for any "super strength" of sasquatch. As for night vision, that would a very selectable trait when one is evolving amongst the megafauna without the benefit of fire, in terms of not only locomotion, but also predator evasion, and hunting. Every slight advancement of enhanced night vision could prove an enormous edge depending on the specific context, couple that with a bottleneck or two where the ability to see at night even just a little bit better than the average bear was a part of avoiding extinction, and those that can't don't make it to the next dance, puts you and yours on the path to continuing and most likely improving that trait. Toss in progressively developing cognition, a hallmark of our primate family tree, and you have evolution occurring in both the physical and mental planes, which can't help but begin to impact each other and push it all the further.