The place in which the book is set in? Concepts with which the book deals? Any allusions? Answering one of those would be great :]
You seem to be in the beginning of the book by the questions you ask.
The only allusion or reference I can think of is to the Hulks. The Hulks were prison ships off the coast of Great Britian. This is really more a reference because of the time in which it was written. Today, it could be considered an allusion because it is not necessarily a current practice.
I guess another possible allusion in the beginning is Georgiana. Georgiana Cavendish was a Duchess of the era. Dickens could have been alluding to her. I have attached a link to maybe uncover a possible link there.
The beginning of the book is set in some nameless town out in the marsh country. Much of the later action in the book takes place in London.
Perhaps the most important concept that the book deals with is ambition and its consequences. Pip has great expectations -- he wants to become a gentleman. But his ambition sort of warps his personality for much of the book. He stops acknowledging Joe because Joe is poor. He is not willing to accept Magwitch because he is a convict. He owes both of these men, but is too snobby to be nice to them