There's probably no significant difference between editions. It's common for textbook printers to make minor changes so they can sell new books each year. Otherwise, almost all of the students buy used. I don't know if that applies to this book, but it probably odes. The only thing I would think would really be subject to change would be anything they have on photoshop. I mean, the idea of light diffusion or framing pictures, the basic principles of color film, the concept of an adjustable aperature, etc., hasn't changed in the last year, so a year old copy should be just fine.
Also, you may consider looking in used book stores, or see if your local university or community college has any used. Off-campus book stores are generally far cheaper than on-campus book stores, if you've been looking at those.
As far as a digital SLR, you'll find that Canon and Nikon are the most reccommended. Some people swear by one, and some people swear by the other. They're both very high quality, though. I use a Nikon D70, and I think it would be impossible for me to be any happier with it than I am, as an introductory digital SLR camera. I absolutely love the thing. Nikon also has the D50, which is very similar, but slightly downgraded, and significantly cheaper. You can get them for around $500 to $600. THe D70s (the current version of my two year old D70) is a little over a thousand. Canon has some comprable models that the Canon shooters would know more about.
Look at the camera reviews and feature lists, and the side-by-sides at
http://www.dpreview.com/