First of all, the FAQ will never cover everything—it will cover the Frequently Asked Questions. Secondly, the FAQ is under construction, so at the current time we know it doesn’t cover everything. Thirdly, we may have overlooked some things, and if you think that is the case you might consider reading on to find out how to contribute to the FAQ.
However, we strongly advise against mailing GRRM as a first (or even tenth) resort when you’re trying to find the answer to a question. GRRM gets a lot, and we do mean a lot, of fan mail every day, and we’d all like the next book to be out as quickly as possible, right? What we instead suggest is that your first recourse is to turn to one of the following resources: The FAQ, the A Song of Ice and Fire Forum and the So Spake Martin collection. You can also try the search engine (to search through all of Westeros) or .(JavaScript must be enabled to view this email address) of Westeros.