Who is Fawcett from Casino Royale and what is their importance?

Fawcett, a former member of the British Navy, was recruited by the Secret Service for work in the Carribean. He was trained in the art of photography and officially performed his duties under the cover of being a photographer for the islands' main newspaper the Gleaner. Fawcett acts as an intermediary, he collects and passes information.

Fawcett's that guy from the Gleaner newspaper in Jamaica who used to be in the navy. Secret Service recruited him after the war, trained him up as a photographer for cover, and he just handles the message-passing stuff for Bond on the assignment. Pretty minor role overall, basically just the go-between for intel.