Generally speaking, once the water pipe exits the heated bay, the water distribution is "inside" the RV to the extent that it won't freeze because you've got the RV heated to an acceptable human-comfortable "room temperature". As for specifics of pipe runs, hot & cold water makes its way under the shower to get to the shower and kitchen faucets...but again, these pipes are "in" the heated area of the RV vice exposed to outside weather.
My experience with zero-degree weather was satisfactory. No problems. And yes: turning off & draining the refer's ice-maker feed (including the electric-operated valve) should be done.
Robi & Dale ---- Go Navy ----
2016 Winnie TOUR 42'
Tow: '19 Buick Envision
or: '08 Buick Lucerne