Who was James Granger and how does he relate to Granger, the intellectual hobo?
Your question identified the importance of naming in the novel and how by giving a particular name to a character an author can suggest a lot about that character by the associations of the name.
Well, James Granger was born in the United Kingdom in 1723 and died in 1776. He studied at Oxford University and then entered the Church of England. He is famous for his publication which is entitled a Biographical History of England from Egbert the Great to the Revolution, which was published in 1769. Interestingly, he himself stressed the value and importance of collecting engravings of portraits. He was owner of his own collection of 14,000 such engravings, and encouraged others to make such collections.
This is where I think we can draw a link between this real character and the fictional Granger in Fahrenheit 451. Granger in the novel is a collector of texts, as a member of the book people. Both Grangers are avid collectors of information, and James Granger tried to systematise the information he collected, which is what Granger in the novel tries to do, but albeit under very different circumstances.