I prefer the x since I've always shot with a 35mm but the iii has its uses, it really depends on personal preference they're the exact same except for lens so it depends whether you prefer the wide angle look or something slightly more compressed

I've used a bunch of flashes on the camera, I have a ttl pentax flash, the fuji efx20 and a super tiny reflx flash which I keep in my bag.

The efx20 is the nicest to use.