Corwin's Series -- Remember that virtually all that occurred in the Corwin series was spoken as a tale to his son. Except where another Amberite can back up the statements, take everything Corwin says with a small siberian salt mine. That said, here are some specifics.

The PCs do not know about Primal Pattern. They heard of damage to Pattern, but never got to see it except when they walked it.

The PCs are aware that the Jewel of Judgement exists, and have heard rumours of weather control. No other rumours or knowledge of the Jewel are available to PCs at this time.

Fiona is known to have held Brand with her mind at the Abyss. She is not, however, known to be able to create portals through Shadow.

Chaos is mostly unknown to the PCs, what they do know is rumour and wild stories from the troops that went with Benedict.

Under orders from Oberon, all the youngsters who were in Amber at the time were kept there.

The PCs who were in Amber at the time saw Oberon's body pass out of the city, carried by what appeared to be demonic pallbearers. Rumours abound of dragons and the like when his body passed into Chaos, but those were not seen.

Merlin's Series -- A lot of what Merlin went through in the books, you'll want to view as being in his diary - meaning that no one knows it but him, unless he told someone.

It is known that Merlin is Corwin's son. He is also currently King of Chaos.

It is known that Rinaldo, AKA Luke, killed Caine, and was later pardoned by Vialle and Random.

It is known that Merlin's half brother from the Courts, Jurt, attacked Merlin at several points, and that there is a construct known as The Fount of Power that aided him. The nature of the Fount, its location, etc. are not known.

It is known that Oberon sired Dalt and Coral. It is believed, from overheard statements, that Coral carries the Jewel of Judgement with her, though it is not known how.

It is known that damage to Castle Amber seems to actually heal. Not one Elder has stated any theory - publicly - as to how that works for something so large.

It is known that Corwin's sword Greyswandir is a Pattern blade, though not how he came to have it, or how it was forged. Greyswandir is the only known Pattern blade, though there is speculation about Bleys' sword.

No one in Amber knows (or if they do, is telling) about anything called Logrus. All that is commonly known about Chaos is that they're shapeshifters. There are rumours that Merlin had access to a Power nearly equal to Pattern.

No one by the name of Mandor is known in Amber.