How do the Starks and the North save and store their food for winter? Do they salt it, or smoke it, etc. Do they make preserves out of fruits and vegetables? What do they do for drinks?

We see both salting and smoking used to preserve meat.

Pickling is used for vegetables, so I wouldn’t be surprised if there’s a good bit of preserves-making. 

For drinking, there’s water, beer, ale, wine, etc.