Name: Elise Fairfield
Year: 3
House: Ravenclaw
Should you be able to drink and eat anything you like in the library?
No. Eating anything you like should be banned in a library, even a magical one. Firstly, although it is a school of magic, discipline still needs to be practiced. Discipline is essential in any one person's life and should any of the Hogwarts students ever need to use a Muggle Library, they might be a little destructive with the food and as for charming the books to repell stains, the stains in question would not happen if there was no food in the library.
However, I think it would be acceptable if the person in question has a medical condition which requires them to eat at regular intervals. In that case, there should be a list of such people and the foods they bring in should be within reason and not overly greasy.

Is the library supposed to be a center for drama or learning?

Library by definition is a place set apart to contain books, and therefore should be a center for learning. Of course learning comes in all its forms, and adventure can also be a form of learning. However sir, Drama is a genre of books and therefore this would be a trick question.

However, the drama you meant is likely to happen anywhere, it would simply be wise to advise the students to keep it down so that the environment remains one conducive to learning.