Seanchan is the name of the continent which lies nearly three thousand leagues across the Aryth Ocean.

Pre-Invasion Seanchan :
Seanchan was a constantly shifting quilt of nations of various sizes most ruled by Aes Sedai.
Aes Sedai, who made open use of their power formed temporary alliances with one another.
Assassination was the most common cause of death among Aes Sedai and among all who achieved power.

Conquest :
Eventually Luthair Paendrag, whom the Seanchan had begun to call the Hammer,

There's nothing explicitly wrong with this but I thought there was vis-a-vis the so-called Dark Prophecy in Fal Dara which refers to 'the seed of the Hammer'. What I'd forgotten though is that Verin explains that AH was also known as 'The Hammer of the Light'.

forced his allies to remain loyal and went on to conquer the continent.
The Conquest also called the Consolidation required nearly three hundred years, and another two centuries passed before the last resistance was expunged and Luthair's descendants reigned a land totally at peace, so far as any empire can be at peace.

The imperial banner is a wide border of royal blue around a box of white inside which a golden hawk in flight clutches three lightning bolts in its claws. If the Empress or Emperor is present, it is fringed in gold; if the heir to the throne is present it is fringed in blue.

Damane :
The first a'dam was made by an Aes Sedai, Deain.
There is no doubt that the current power of the Imperial family over an entire continent is directly linked to their subjugation and control of all Seanchan Aes Sedai. There is little doubt that the knowledge of the true nature of Sul'dam was suppressed, certainly it was lost within a hundred years.
They are sometimes horribly mutilated for punishment, as it is possible to channel without hands feet or tongue.
The damane are not only used as weapons, but also aid in construction of large bridges ...
Some damane are also used to heal the sick
Frequently however their Healing is rejected because of the belief that they are not human.
The abilities shown by damane differ widely from those displayed by Aes Sedai in many areas.

I'd certainly like to know what they can do that the AS can't. Some 'lost talents' maybe (obviously they don't know squat about gateways)? Or is this just a reference to their greater prowess in combat ?

Class Structure :
A nation that is stratified with very little movement between the ranks.
The lowest class in Seanchan is usually the da'covale, or those who are property, or simply covale, property.
Seanchan simply absorbed its invaders, who quickly adopted the pre-existing social norms.
So'jhin the hereditary upper servants of the Blood, outrank free men and women. - it is one of the few ways to advance beyond one's station of birth.
Today it is possible though rare, for even a common soldier to be raised to the Blood.

Appearance :
Physical manifestations of rank are essential.
Hair.
Members of the Blood shave the sides of the head leaving a crest.
A Voice of the Blood will wear the left side of the head shaved and the right side braided.
A Voice of the Throne will shave the right side and wear the left side braided.
Members of the imperial family shave their head completely.
Commoners do not shave any part of their heads.
No one displays baldness publicly.
Nails
All nobles beginning with the lowest wear long exaggerated nails, lacquering at least their little fingers. High Lords or Ladies paint the nails on their ring fingers as well.
Members of the royal family have three painted long nails, on the little finger, the ring finger and the middle finger.
The ruler will have all five nails painted.
Each Lord or Lady's nails are lacquered in the colours indicative of their House.

Imperial Rule :
The Crystal Throne itself is a great ter'angreal that causes anyone who approaches it to feel immense awe and wonder.

Here's hoping that Mat makes an appearance at the Court of the Nine Moons :)

The members of the Imperial family and of the Blood also seldom speak directly to anyone of lesser rank then themselves save to bestow an immense honour upon them. Most communication is done through a Voice, a servant, usually hereditary, who actually speak for his / her master or mistress.
Subtle non-verbal gestures from the master. It is forbidden for a person of lesser rank to make eye contact with one of a greater.

Honour :
To them, a word of honour once given, is considered absolute.
The word sei'taer literally means straight eyes or level eyes in the Old Tongue. Sei'mosiev = lowered eyes or downcast eyes.

Deathwatch Guard :
Though the guard are actually the property of the Imperial Personage they are often loaned to others.
Ogier make up a portion of the Deathwatch, although they are the only ones not property, and are considered incredibly fierce and more deadly than their human counterparts.

Well, you could knock me down with a feather. Let's hope they make an appearance.

Imperial Justice :
Seekers for Truth, a police and spy organisation belonging to the Imperial Throne. Chosen from all strata of society, though, usually not of the Blood - though the proportion of Darkfriends does not seem to be any less than before the Seekers began their hunt.
Tower of Ravens - the central Imperial Prison.
Since no one may spill a drop of blood from one who is of the Blood, the torturers have been forced to devise non invasive but excruciatingly painful methods of questioning the nobles housed there.

Miscellaneous : Warriors' and nobles' swords have thick curved blades with a back edge one quarter to one third the length of the blade, a two handed hilt, and quillons shaped like a C or a crescent moon. The sword pommel is a cap. Among nobles the cap is usually formed in the shape of an animal's head, the hilt itself is sometimes worked in the figure of a woman, say, or a fanciful creature, and the sword and scabbard are ornate with gold and gems.
Seanchan warriors also use spears which are decorated with tassels in the house colours and shields which are lacquered also in the house colours, except for the Deathwatch Guards whose colour of both spear and shield is black.
Both the Tower of Ravens and the Court of Nine Moons are located in Seandar, the other major cities in descending order of size are Kirendad, Noren M'Shar, Asinbayer, Qirat, Imfaral, Sohima, T'zura, Anangore, Shon Kifar, and Rampore

The Forerunners & the Return :
More than five hundred ships of all sizes called themselves Hailene, or in the Old Tongue, Those Who Come Before or Forerunners.
Return, consists of thousands of ships and hundreds of thousands of people, the Corenne's invasion fleet has been in the planning for over a century.