Looks really nice. I find it very intriguing about the differences of how people have there slabs installed. I know it mainly deals with landscape and the type of environment (climate) a person lives in but its really neat to see how folks install there slabs in there area.
Here in Northern Texas our ground seems to be flatter than most but if not we just haul in lots of dirt and build a dirt pad first. Roll, pack, and water many times and then dig the beams out and possibly a footer in corners if needed. They are almost like a floating type setup. It is normally all one big piece in 1 pour usually.