The number of parts and size of the index structure is configurable, but there are three stardard configurations, small, medium, and large. Small takes about 15MB of disk space, medium takes about 150MB of disk space and large takes a large amount of disk space. In addition to these three standard configurations, I created the tiny configuration that only takes about 2MB of disk space.
You can run about 17 types of transactions on the oo7 database. See OO7.cc for the full listing, but below are the ones I often use.