Answer to Question 1
National saving increases when the government runs a budget surplus unless private saving decreases by the amount of the budget surplus, which is unlikely. National saving decreases when the government runs a budget deficit unless private saving increases by the amount of the budget deficit, which is also unlikely.
Answer to Question 2
The demand for a particular brand of orange juice will be more elastic. There are many close substitutes (other brands). There are fewer substitutes for orange juice.