Lemons are not all the same! There are small, medium and large lemons… juicy and dry lemons. There are too many variables in juicing a fruit to give an exact amount, but…
A general rule of thumb is 1 ounce of juice in each fruit. I have had lemons yield as little as 1 tablespoon to as much as 5 tablespoons, but an average healthy medium sized lemon with provide 1 ounce.
1 ounce = 2 tablespoons = 1/8 cup of juice
The same premise as above applies, each fruit is different. In general a lemon typically yields 1 tablespoon of zest.
How to store lemons?
Citrus should be stored in zip-top bags in the crisper drawer of your refrigerator. To learn more about food storage read How do I store food in the refrigerator & freezer?