One of the odder things about the recent stream of articles about this book is that a lot of people have been asking for updates and information about the book that has been readily and freely available, in some cases, for years. I have maintained a collection of information on ADWD over on Westeros for three years which answers these questions, but clearly people haven't been able to find it, so I am reposting it here.
Obviously some SPOILERS are contained within, so read the rest of this article at your peril!
You are now entering a Wertzone Spoiler Area. And no, I'm not going to screw around with my blog's html to put the cut thing in, that's the sort of thing they should put in the edit bar like Livejournal does and Livejournal is like a decade old, but anyway I digress.
"Which POV characters are in the book?"
Varamyr Sixskins (prologue-only POV)
A 'new' POV who is probably, but not confirmed, Melisandre of Asshai.
EDIT: I have been informed that in Spain last year, GRRM was saying that he had written a new Areo Hotah chapter. The presence of this character in ADWD was previously unknown.
EDIT2: GRRM had previously said that Sansa was a POV character, with a single chapter. However, this chapter has now been moved into The Winds of Winter, and she no longer appears in ADWD.
"Which characters will have the most chapters, and how many will they have?"
Jon and Dany, 9 and 13 respectively. Note that this was GRRM's plan some time ago, and may have changed in the interim.
"What about Tyrion?"
Originally he had 5 chapters, but GRRM expanded these to 7. This was just after the split, and it is possible additional chapters have been added or subtracted since then.
"Which characters will have the fewest?"
Bran, 3. Same caveat as before. Quentyn also only has 1 confirmed POV chapter (and is a hold-over from the AFFC Martell chapters), but from some of GRRM's comments it sounds like more may have been added.
"Will we find out the fates of Cersei and Brienne?"
Yes, but only if there is room for an epilogue or series of short chapters at the end of the book that can touch base with what the AFFC characters were doing at the end of that book. To be honest, I wouldn't bet money on this happening.
"Will ADwD’s timeline substantially extend the overall series’ beyond AFfC’s?"
It will cover a period several months longer than AFFC.
"Hang on, won't that make re-synching things a bitch in The Winds of Winter?"
Yes. I imagine this is a contributory reason to the many delays on the book as GRRM doesn't have to just 'finish' ADWD, but do so in a way that satisfactorily sets up TWoW as well.
"How long will the novel be?"
The book was originally estimated to have be between 1100 and 1300 manuscript pages, coming in somewhere between the length of A Game of Thrones and A Clash of Kings. GRRM's last official update said that the book is "getting longer," however, so it could be more than that. Note that 1500 MS pages is the length of A Storm of Swords, and represents the upper limit of the book's size.
"Will there be new maps, and if so, of where?"
There will be a new map of the Free Cities. According to some sources, GRRM does have a map of Braavos as well, but it's unknown if this will appear in ADWD or be held back for the World Book. The landscape between the Free Cities and Meereen will also likely appear in the book, but whether it is mapped or not is unknown.
"Will more happen than in AFFC?"
The book is apparently longer, so from that basis yes, 'more' happens than in AFFC.
"Are there more battles?"
Going by the chapters released so far, it's even with AFFC. I assume more happen later in the book, so this is a reasonable bet.
"Hang on! Davos has POV chapters? Isn't he dead?"
Remember that most of ADWD will cover the same time period as AFFC, and we don't hear any news about Davos in AFFC until quite late in the book. Davos' chapters can therefore take place before Cersei receives that news about him, and of course communications in Westeros can be uncertain at the best of times...
"If that is so, how are Arya and Asha in both books?"
Their chapters in ADWD carry on from their last chapters in AFFC, and take place either during the timeframe of AFFC's last few chapters or after them altogether. Note that their chapters were among those written for AFFC and split between the two books by GRRM when he split the books.
"Does Rickon appear?"
I remember way back when that GRRM said no, he doesn't. Again, this may have changed in the interim.
"Do the Others appear?"
Let me put it this way: the prologue of ADWD fits the pattern established by the prologues of the other odd-numbered books.
"Any more info on Jon's parentage?"
Yes. However, the tidbit that is known to appear seems to cloud the issue further rather than make it any clearer. It's possible additional information will appear later in the book.
"Will we see Asshai in ADWD?"
In GRRM's words: "Only in flashback and memory, if at all."
Sources: GRRM's Notablog, the Updates page on his website and the results of many fan questions, interviews, Q&As and convention readings as collected in the SSM collection on Westeros.org.