I've been running an XS-1 for about two years now. From the traffic and questions, some random thoughts:
Built like a tank. I thought the rubber covering would be weird, but it really works well. My lens does wobble every so slightly at full extension, but can't find any evidence that it interferes with image quality. The zoom lens can creep mechanically at steep 'departure angles', but I've had Nikkors that did this, so whaddya do? The EVF is a standout for me. I really thought I'd have to get used to it, but I took to it like a duck to water, to the point I only compose with the aft LCD on the tripod, where the tilt screen can come in real handy, reminds me of using a TLR. The eye sensor for me works fine.
I've never been able to see any vignetting with the included hood at 24mm.
With the long physical extension as you zoom, you WILL see a shadow of the lens with the built-in flash. I use the Fujifilm EF42 flash with mine (a match made in heaven) and that cures it at any focal length shadow-wise. In the 24, 28mm range, you will see the shadow of the hood with the pop-up flash: Remove the hood at widest wide-angles and you're fine. And like all the X's, the flash capabilities are very fine.
It runs 62mm filters, so you can get anything from any maker, a fairly common size. I run the Fuji EBC protector filter (got a deal, thanks B+H !) and a Hoya polarizer. These are 'standard' depth filters and I've never seen them vignette at 24mm.
I'd get one extra battery, no more unless you plan on extended stays in the rough away from any AC. They last a long time in the X-S; I've burned through one and started the second, but never more than that, even on a day-long museum trip where I did finally have to switch to the second after 400+ frames.
The macro capabilities are immense. Bear in mind, this just doesn't work past 135mm, but there is a tremendous 'sweet spot' macro-wise at around 100-135mm stopped down a stop or two: This allows you some 'back-off' maneuvering room. If I go 'Super Macro', I invariably have to back up, or the sheet-of-paper-thick depth of filed catches me out usually.
I typically run ISO's from 100 to 800 for quality, and run either DPR Auto or 400%, at L4:3 image size.
I'd stick with Class 10 cards. I use either Fuji's or SanDisk in 8gb size: Quicker to unload, and remarkably, I may be the only person that uses them, as they can be had CHEAP ! Some of the other guys have commented on read/write speeds, and I'll leave that to their expertise. Typically I shoot no video, and am a JPEG hobbyist, so I get to skip the software wars and RAW discussions.
The XS was my first digital SLR-ish camera, too. I frankly could not make sense of the 'format' wars between FF or APS/C, much less then to narrow it down to a Canon or Panasonic or Nikon or whoever. Two years later, simple enough, I'll get an XT or XE one day, I've been a Fuji fan since the film days, but not today.
The knock on these cameras is yes, it is a 2/3" sensor, and you don't get the results you'd get with a Rebel or an X100, etc. I fully agree. My long shots certainly don't look like they were taken with a D4 and a 300/2.8, but I saved 7 grand, but I do have just as much fun, and it's a hoot trying to get close to that look with what I have, stretches me to think.
But . . . . the beauty of these cameras is I leave the house with the XS-1, the EF42 flash, a spare battery, a spare card, and that's it. If something particular is involved, I'll take the big tripod and the RR80 remote release. So that's travelling VERY light, and with this, I can take full moon shots, birds in the top of a tree, macros of flowers, family photos with bounce or fill-in flash, just about anything I can think of. This really appeals to me. It's just a very organic way of working with very little. I'm not publishing pro work, I'm not printing 16x20's, and the only RAW I'm used to is a Sushi bar, so for me it works great.
And good on you, what a great deal !

Red Tatra, Lane Motor Museum Nashville, XS-1

' . . . this wasn't the split-window I was thinking of . . . .', XS-1

CZ racer interior, Lane Motor Museum, Nashville, XS-1

Not a boy, just a Gull. XS-1
These are all fine-tuned and/or cropped in Windows Live Photo Editor or the included Fuji Finepix Studio. Like I said, I'm a JPEG guy.