Issue 18

This may well not be perfect. But this should reflect the type hierarchy & matching `Builder`s as discussed yesterday.
Some items are just barely touched on, as they will be addressed when the "real thing" is (e.g. solving topologies at the `Store` SPI level rather than the `Cache` level)
Others may well have been simply overseen. 
I really wanted to get this out for review ASAP! Looking forward to your input.