I would say that the learning curve is very shallow with the K100D. For starters, you can put the camera into AUTO mode and use as a point and shoot. Then go to PROGRAM mode have a bit more control - +/- exposure. Then start using the shutter/aperature priority and play some more.
Finally catch a dose of LBA and buy a bigger bag.
As for photography books, something by Tom Ang is fairly simple and easy to understand.