Dormant means the leaves begin to wilt and brown and lay down. You'll know it when you see it. ;)

Need to water depends on your climate. They will need some water to survive the dormant period but here rain and snow are enough. Mulch with straw is good and just leave the plants under the mulch till spring. Then, when cleaning up the bed in the spring remove any remaining brown leaves after the plants green back up.

Dave