[Note: The following report comes from the kaffeklatsch held at Interaction.]
1. How do you deal with the writing if/when you get to a "sticky" bit that slows you down?
GRRM writes each person's POV story in isolation and then weaves/edits them into 1 piece. So if he gets stuck on, say an Arya chapter, he changes to writing Tyrion stuff and then goes back later.
2. There is a song about the seven gods, but only six are mentioned. Is there a verse that is missing/cut out?
Sorry - got a bit sidelined on this question and digressed to Magic & Gods in Westeros. More about that later.
3. There seems to be an awful lot of suffering in these books (especially the female characters, who get treated pretty brutally). Should we expect the next books to get lighter or darker?
On this one, he said that a lot of the male characters got it pretty rough too - Robb losing his dad, thinking he'd lost his brothers + Arya and then dying. But he said that at least in the short term, it's going to get darker.
4. How important is your fans opinion of the books to you? Would you ever consider making a change for the readers?/Do you know what will happen in Westeros in the next books, have a definite ending in mind for it, or are you now letting the story evolve as you write?
As they were related, I asked this as 1 question. He was a little cagey about it, but he pointed to the planned "5 year gap" between ASoS & AFFC (books 3 & 4 for the layman!) as an example of where fan's opinions - as well as his own efforts, pushed him into changing his storyline slightly. He made the point that his overall story hasn't changed but certainly elements of the sideline stories have become more fleshed out than he'd originally intended. Thats about as much as he went into on that one.
5. You're pretty active on the Internet forums and discussions f your work, albeit sometimes as a "lurker"...Have you ever changed something you'd planned to write because a fan's theory got too close to the mark, in order to keep the element of surprise?
He says he's stopped doing this for that reason! Well not really, but he doesn't change storylines because people have guessed where its going. He just hopes his work doesn't get that predictable!
6: Magic has steadily increased throughout your novels from pretty much non-existant in book 1 to rising prevalence by book 3. Will this trend continue in future books?
"That's a fairly safe assumption, yes". Good news for you magic fans out there I briefly discussed the role of Gods in the magic of Westeros. R'hllor etc. He has ruled out any appearances of "demigods" or direct involvement from the Gods in Westeros though.
7. Will there be life after "A Song of Ice & Fire"? In other words we will see any more stories set in Westeros?
Yes. He's already working on another Dunk & Egg story and plans to continue to putting these out whilst writing his new ASoIF books. Interestingly one of his fans (not GRRM himself) pointed out that he'd mentioned to GRRM that as Dunk ends up as Lord Commander of the Kingsguard and each short story so far has been "a step up" (Hedge Knight, Sworn Sword etc) will he continue making the title of each story another "level". Apparently he's considering it, but hasn't decided yet.
To continue in the same view he has comprehensively ruled out ever doing a 'prequel' novel on Robert's Rebellion. Some ideas he has for future Westeros stories are (and again I stress he has not confirmed yet that he will do these) a novel on Aegon IV "The UnWorthy" from his POV and also a story set in Braavos and the Free Cities - possibly some kind of murder mystery type thing.
For potential future topics, GRRM is very keen on doing a novel set in a Roman-era fantasy world.