For waterproofness, kind of, put on, in order:

Socks
Shoes
Plastic bag (like supermarket bag)
Booties

Yes the bag covers your cleats. Should be okay for most cleat systems (Look, Time, I dunno about Speedplay).

Your feet will be dry for about an hour. They'll eventually get soaked in condensation but in an hour crit they'll be fine (or an hour training ride). The plastic is definitely windproof so that helps with keeping your feet warm.

Cannondale made an outer sock (baggy but water- and wind-proof) that kind of worked like the plastic bag but I didn't know it'd work outside the shoe. I always put it inside the shoe.