I found an interesting website, from the US Department of Agriculture. It’s about raising snails commercially for food. It’s also got good information on their biology.
Winter hibernation: they can bury themselves up to a foot deep.
I had previously found a good blog by an American malacologist (snail scientist) called Aydin Örstan. You can see a PDF published by the American Malacological Society, written by him on Rearing Terrestrial Gastropoda. His blogsite goes well beyond snails, and is fascinating and fun:-- http://snailstales.blogspot.com/