BW Combs , Feb 19, 2008; 07:24 p.m.
The best setup for digital interior photography and what one can afford are on opposite ends of the spectrum.
But, I digress.
A Nikon D80 would work fine. You will need a good wide angle lens like the Nikon 12-24mm, Nikon 14-24mm, Tokina 12-24mm or similar. The 18-55mm lens you mention is not really wide enough for interiors. You also could use a Micro lens, such as the 60mm or 105mm, to help capture some detail aspects of your labor.
Lighting equipment is also nice to have in your box of tools. Several Speedlites (SB800) would help. Combining your ambient light with the control of speedlites will give you more natural, pleasing shots and reveal details. Also, lighting stands, tripod, etc.
Careful composition and planning of a shot will drastically reduce any perspective oddities, and most can be corrected in post processing, if necessary.
A PC lens, or perspective control, is helpful in correcting the image, but they are not wide enough to start with for interiors on a digital camera.
I applaud your quest to capture images and records of your work. In fact, you will probably find that the process of photographing your interiors will expand into another tool you can use to create those interiors. You will see things you never saw before through the viewfinder.