The forum based one we have now is fairly accessible through the mega-directory (just ctrl+g and type "market" or whatever) and easily editable.

Like royal said, I'd divide the current FAQ into sub-forums; it would add some sort of structure to the FAQ (sorting in alphabetical order isn't exactly the easiest way to search). Using .php might sound pretty accessible in theory, but the amount of time it would take to sort the FAQ into translations would suck and likely take awhile.

So I'm pretty much recommending that we just make the current FAQ we have more accessible rather than mass-overhauling it to .php; it's a lot of work for not a whole lot of reward. There's no major incentive that comes from doing it.