What atmospheres are suggested by the settings of the marsh and London in Great Expectations?

(Because only one question can be asked at a time, your
posting has been edited.) 

It is ironic that Pip so eagerly
moves to London in his desire to become a gentleman, for the atmosphere there is one of
squalor, crowding, and corruption.  When Pip first arrives in London and traverse the
street towards the offices of Mr. Jaggers, he is stunned by the appearance of the
place.  The room is lighted by only a skylight; there is dust and grit and papers and
other debris littering the floor.  When Pip tells the clerk that he will "take a turn in
the air," and goes outside, he is taken aback by the grim stone building known as
Newgate Prison.  The roadway near it is "covered with straw to deaden the noise of
passing vehicles."  Smells abound, especially of "spirits" and beer. Various unsavory
types enter Mr. Jaggers's office while Pip waits for the unscrupulous
barrister.

At his meager apartment where Pip goes to
live with Herbert, there is a watchman who stands outside the building.  The lodging in
Barnard's Inn where he and Herbert are to live is described by Pip in his
dismay,

the
dingiest collection of shabby buildings ever squeezed together in a rank corner as a
club for tomcats...a melancholy little square that looked...like a glant burying
ground.  I thought it had the most dismal trees in it, and the most dismal sparrows, and
the most dismal cats, and the most dismal houses that I had ever seen.  The windows of
the houses were in every stage of dilapidated blind and curtain, crippled flowerpot,
cracked glass, dusty decay, and miserable
makeshift.

It is no wonder
that Wemmick lives outside the city in his "Castle" with its drawbridge in a quaint
little bucolic area where he has his fowls, and rabbits.  Behind this area is a
miniature fortress with his cannon that he sets off for his Aged
Parent.

In contrast to the dingy, smelly, miserable squalor
of London whose streets abound with thieves and unsavory types, the marsh with its
sluices and dams, its wet grounds and its cows wear a "respectable air" as Pip has
remarked upon leaving them.  The forge with its warmth and the love of Joe within offers
a haven for little Pip from the abuses of his sister.  The marshes are spacious and
although damp and foggy, they have the smell of nature about them, not the smell of
urban squalor. Always there is love in the humble home of Joe.