Stone can make a great base. Because of stone's sense of permanence, a stone base can anchor and establish a structure firmly in place. Larger stones in an irregular pattern create a firm base that complements the lightness of the structure above.
I like the concept of the bottom floor/rooms extending to the outer edge of the porch upstairs. It eliminates the overhang of an upstairs porch which can often make a lower level/basement seem dark.