I ride in the conditions you describe although moisture content is lower. Temps around freezing are tolerable, but much below it is time to go skiing.
I have found neoprene socks to be the best. They aren't too bulky and retain any warmth you create. Socks such as these:
http://www.nrsweb.com/shop/product.a...0&pdeptid=1168
Also my shoes do not vent. Not a lot of mesh.
S