Short answers, pulled from the story.
The Royal Exchange was founded by the merchant Sir Thomas Gresham, on the suggestion of his factor Richard Clough. Queen Elizabeth I officially opened it on the 23rd of January 1571, awarding it the royal title and a licence to sell alcohol and valuable goods.
The Royal Exchange has been destroyed by fire twice. Gresham's original building was lost in the Great Fire of London in 1666. The second Exchange burned down on the 10th of January 1838 in a fire caused by an overheated stove, the blaze visible from Windsor 24 miles away.
The current building was designed by Sir William Tite, who won a competition in 1839-40. Queen Victoria opened it on the 28th of October 1844, though trading did not commence until the 1st of January 1845.
The Gresham Grasshopper is the golden weathervane on the Royal Exchange's clock tower, taken from the crest of founder Sir Thomas Gresham. It is 11 feet long, stands 177 feet above street level, and was rescued from the fire of 1838. According to legend, a grasshopper's chirping once led to the discovery of a foundling who became Gresham's ancestor.
The steps of the Royal Exchange are a traditional site for reading certain royal proclamations, including the announcement of a new monarch's reign. Following the confirmation of a succession by the Accession Council, a herald proclaims the new monarch's accession at the Royal Exchange building.
Paul Julius Reuter established the Reuters news agency at 1, Royal Exchange Buildings, directly opposite the Royal Exchange, in 1851. A statue of Reuter stands in a lane by the eastern entrance to the present building.