So in your sentence it would be 'in the field of literature' without a capital letter.

Not normally, no. For example: I really like literature. I love French literature. Make sure you read the literature. The only time you would capitalise literature is if it is a proper noun e.g. the name of a degree. I have a degree in English Literature.

In that sentence, no. Only if literature is part of the name of something: "I am taking English Literature this semester"

*have