Here are some helpful tips for preventing and thawing frozen pipes:
American Red Cross
American Red Cross Fact Sheet: Preventing and Thawing Frozen Pipes
HGTV - Avoiding Frozen Pipes
Here are some helpful tips for outdoor plant care during cold weather:
Tender potted plants should be moved inside, or at least close to a heated structure for protection. You can try to cover delicate, valued plants with blankets or breathable tarps. Plastic sheets will not help. For annual beds with newly emerging seedlings try sheets of newspaper with a light cover to keep them from blowing away.
All of your plants should be well hydrated. The added Santa Ana wind conditions may cause many plants to suffer dehydration.