A serving of rice I just made is 1/3 cup. Do I measure the pre-made rice or the expanded rice?
The expanded rice. If a recipe or diet calls for a measure of uncooked rice, it will say uncooked rice.
Depends. What is defining the serving size? If you’re looking at the back of the rice package, doesn’t it say whether it’s talking about dry or cooked rice? Most packages say something like “Serving size: 1/3 cup dry (about 2/3 cup prepared)”
If you’re on a specialized diet of some sort, you need to ask the publishers of the diet whether they mean prepared or dry rice.