The worms go into a dormant state until they're brought back up to room temperature. Just don't leave a piece of food in their box or it will get moldy and ruin your worms. You can take out a few feedings worth at a time to gutload prior to use.
fridge is fine. bottomist shelf is best just in case any stuff dose get out :S that way it stays away from your foods. also take great care the DONT GET WET (from somting leaking ect) as the ammonia in their poo is intensified which not also causes a horrific smell but isnt plesnt on your chest