"What?" "Huh?" "Hm?" and "Hang On..." respectively.
If you're going to talk about these things in an educational manner, properly assuming I know nothing about them, some kind of link or at least explanation would be appropriate.
- in the first draft of original ADWD there was supposed to be a 5 year gap between ASOS and ADWD. GRRM soon realised that he has to rely on flashbacks too much and indeed started writing AFFC to bridge the events. The book quickly became too big and hence the split
- I believe he had problems with timeline (which of the suitors arrives when and how) and then what to do with Mereen once Dany is taken away by Drogon. He fixed that by Barristan POV supposedly
- Barristan POV which he introduced very very late into the process of writing the book (2009 I believe?). Quentyn is basically believed to be leftover from before that event
- look at the gap between the books. GRRM started writing a book and like halfway through decided to scrap it altogether, then again, again, introducing more plotlines, more povs, scrapping all the material again because he thought it doesn't work (that's mostly tied to Mereenese Knot), finally moving 200 pages and Battles of Ice and Fire (Qarth and Winterfell) which were supposed to be the climax of AFFC/ADWD to TWOW and leaving the plot hanging without completing certain arcs
I may be twisting facts as I've only finished ADWD last week, but I believe it's more or less like that. Basically, his work on AFFC/ADWD was an absolute mess.