Food Nutrition and Health - Aspartame

Can you help me out with the following questions?

We learned about the use of sugar substitutes in the North American diet.

Can you answer the following for Aspartame
(a)   Describe the chemical composition & characteristics, including the metabolites produced from its
digestion in the human body.
(b)   Describe the benefits and/or applications (including amount of calories provided, foods in which it
is normally used, etc)
(c)   Explain why foods/beverages with aspartame must show the statement "contains phenylalanine"
on the label.
(d)   Explain why products containing aspartame must bear a best before date on the label.

I am looking for more of personal notes instead of internet resources.
Thank you!!