A bit of an answer (until someone has more):
1. I deeply doubt these are refurbs. MacMall would list them as such if they were, and I bought a new MBA revA at Best Buy for $1249 about six weeks ago. The prices for new have dropped since then.
2. Yes, absolutely Apple will honor the warranty. (And you might want to get Apple Care sometime before the first year runs out.)
3. I can't answer this one. I'm not using Photoshop.
4. Besides core shutdown: high heat (related to core shutdown), lack of ports, small hard drive, lack of optical drive (unless you add on hardware), and such. But I'm sure you already know these general limitations.
For what it's worth: I knew what I wanted and needed in a laptop, so bought the revA MBA with eyes wide open. For me, it's been the perfect machine. I like to write outdoors when I can, and the MBA's glorious screen makes that possible in any light, even in full sun. I don't play games on this unit (use my iMac for those). I've had no trouble watching video: I watched a two-hour stream from hulu yesterday. Things heated up a bit, and the fans kicked on, but otherwise worked fine. (I didn't use full screen, though, which I think causes more stutter.) I've also watched DVDs and rented movies from iTunes, no prob. Basically, I knew I wanted to keep this unit lean and uncluttered with distracting apps--and it works brilliantly as a portable work tool and occasional entertainment-center-on-the-go. Love the build and feel. Love the minimal weight. Love the backlit keyboard (didn't think I'd care about that). LOVE the screen. And it's plenty peppy enough for what I do. Oh, and surfing the web has never stressed it out or caused the fans to rev.
One note: I have disabled the Dock (via OnyX), which may ease somewhat the workload on RAM.
So, as long as you're aware of how the MBA does (or doesn't) mesh with your needs/wishes, you should be fine. If you get one, enjoy! And may you live a long and fulfilling life together.