Chaos is a city patched out of millions of fragments of shadow. The World Wide Web provides a nice metaphor: the web pages are pieces of shadow, hot links the short shadow paths connecting them. There is no overall geometry to Chaos, just a logical topology, one gigantic directed graph. If you know the right shortcuts, you can get anywhere very quickly. But if you stray from the main paths without knowing where you're going, you can be lost for decades -- there is no handy giant "back" button hanging over everything.
Some shadow paths stretch will out into Shadow proper, out to perhaps a third of the way to Amber. The entrance seen in Corwin's Chronicles is just the main entrance, by far the most convenient to march a large army in.
Like the web, Chaos is constantly changing. The main thoroughfares have been basically stable for hundreds of years. The connections on their fringes change consistently. Perhaps a person will realize she's spending a lot of time travelling to the market, and build herself a shortcut straight there. Or the complaints of the neighbors will force an individual to move his entire Ways to a less fussy subdivision. Or she'll just feel like redecorating, or hopes a few more shadow links will improve her business.
Just as the majority of the WWW is in English, the majority of Chaos is under Earth-like conditions: nitrogen-oxygen atmosphere, near Earth gravity, etc. It's just more convenient that way: you're not always shapeshifting and you don't have to worry about those papers you're carrying spontaneously combusting.
But just as the web is not all in English, the makeup of Chaos is hardly homogenous. Almost any environment imaginable is in there somewhere. A single step might take you an underwater fairyland, or to the surface of the sun. Most areas allow magic. Some allow technology. For a few the concepts don't even apply. Some places are completely incomprehensible without years of study.
Given the above, I'm only going to attempt to paint a picture of the very largest thoroughfares and areas in Chaos. (I may try to scan in a rough map, as well.)
The main path into Chaos from Shadow proper is the Great Way. The set of shadows most immediate to it is Rathbane, sort of the trendy, upscale region of Chaos. Most of the newer ways are built here.
The Great Way branches into two main paths, the Low Road and the High Road. These travel through the four main common residential areas, the four Cooleys. The older road, the Low, goes through the older areas, First and Second Cooley. These are definitely the lower class sections of Chaos. The newer High Road goes through Third and Fourth Cooley, roughly speaking the middle class housing areas.
Both roads terminate in Mourne, the historical section of Chaos. In the dim reaches of memory this was all of Chaos. It still holds the seats of government, the Logrus, and the Ways of the older houses.
Central to all (remember, Chaos doesn't follow any sort of sensible geometry) is Kesh, the market district. Think Mallworld. Think the Bazaar on Deva. Think the Mall of America. Think the Bazaar of the Bizarre. Then think much, much bigger -- millions live here. If someone sells something, you can buy it here, be it merchandise or services.
Also central, effectively, is the great jungle Dun Mórdha, ancestral stronghold of Ó Mórdha. It is fair to say it is the Chaos equivalent of Arden, sprawling, expansive, and teeming with life. It's last owner was Falba Ó Mórdha, who was killed in the war; the heir apparent, Samhaoir, has not stepped up to take the place. It is said that criminals inhabit the place now.
Legends say that whoever travels to the heart of Dun Mórdha will find the weapon he needs to face his foes. It's a spirit quest of sorts, widely considered as hard as walking the Logrus, with less reward. As such, it has fallen out of fashion. Few have succeeded since Dworkin came back with a certain Jewel...
The houses of Chaos are a sort of loosely organized quasi-hereditary guilds. They group people together based on traits and callings. Most houses provide automatic membership for children of members. Most also provide a way of earning membership. The rules can be quite arcane, and differ from house to house.
Power in Chaos rotates from house to house. Okay, maybe rotate isn't such a good word. Lurch randomly might be a better term. There is a cycle. There are exceptions. There are trades, power-plays, and outright thefts of position.
Sigh. Let's get right to the house list...
Note that I've used the names from the second series, but largely thrown away the context.
Honor is all important to House Hendrake, with being damn good warriors a close second. As long as the proper niceties are respected, all forms of combat skills are embraced. Their ways are located in Mourne. Perhaps a third died in the war.
Bravery is the defining idea of House Helgram. (Though many in Chaos claim "foolhardiness" would be a better word.) Charging into vastly superior forces is considered normal. Organization tends to be frowned upon as cowardly. Think of the Scottish in Braveheart... This house suffered massive casualties in the war.
Control is the defining notion behind House Chanicut. Utter and total control over themselves; as much control as possible over any situation they find themselves in. Their discipline replaces shapeshifting with fine control over the individual cells in the body. Membership must be earned, and members generally have no children. One precept: "There are only necessary actions and mistakes." Only a few members fought in the war.
House Jesby contains the merchants of Chaos. Your typical member is a great salesman and an expert on what it is he's selling. They have fairly strict rules on property rights and quality control, but price-gouging is considered almost a duty. Will sell anything. Ways located in Kesh.
House Veda are provide the servives. Any services. For a substantial price. A typical member will be expert in a few fields, and know just how to put you in touch with somebody who can help you with anything else. Ways located in Kesh.
House Wellsbri provide participatory, real time/space simulations. This is Chaos's equivalent of Broadway and Hollywood. Ways located in Rathbone.
House Swayvill are the diplomatic core of Chaos, roughly equivalent to the lawyers and politicians on Earth, only not always so slimy. They're located in Mourne.
House Sawall are the generic scholars of Chaos, classic Ivory tower types always getting further into the nature of the universe and further away from plan old common sense. Ways are in First Cooley.
House Minobee are the critics of Chaos. No, wait, they're worse. They're artistes. Totally self-involved, they do sick and twisted crap because they get a vague rise out of it. They are to be avoided by sensible folk. Ways are in Fourth Cooley.
House Lenamore are the musician/mathematicians of Chaos. While their pursuits can get a bit far-out, they still stay relatively close to earth. Sort of wandering bards/problem solvers. They have no ways.
House Farkid are the priests of the Snake, guardians of the Logrus. The fact that most Chaosites ignore the religion doesn't make it any less true. The priests just shut up and make sure the proper rituals are observed. Ways are in Mourne.
The distinguishing characteristic of House Nostri is that its members' primary form is a feline humanoid. Membership is largely hereditary, though it is possible (though extremely difficult) to shift your primary form. Warlike pursuits are common, though by no means universal; perhaps a quarter of the population was lost in the war. House unity is very strong. Ways are in Second Cooley.
The members of House Nim, on the other hand, would claim to have no primary form. They are the master shapeshifters of Chaos. Their ways are off Rathbane, and require very gratuitous shapeshifting just for basic survival.
It's perhaps an exaggeration to call Seskin a house. They are loosely affiliated wanderers who take advantage of the crazy interconnectedness of Chaos to live off the land, so to speak.
Chaos being what it is, there are zillions of family names there. But there are only a few really notable families. Here's an overview, arranged from oldest to newest.
(In case you were wondering, there is no fixed tradition for how the family name passes on.)