Trying to make sense of an iRobot Create setup

Well, I have been trying to figure out how to wire the RPi / PiFace / iRobot Create (iCreate) / SSC-32 so that I can do what I want to on the iCreate both on the bench and mounted on the iCreate.  So far my test setup is as follows:

So far, what I haven't shown in this diagram is the connection wires between the iCreate DB25 connector and the PiFace.  I have decided that they will of necessity have to go through a protoboard.  The PiFace will also be connected to a distance sensor.  The actual control for movement will be done by serial connection (the iCreate USB to serial cable) to the iCreate body.  This stems from the fact that I have not figured out which pins are going to do what with the interface.  I can put this test setup together over the course of a few weeks. I do show a temporary connection to the RPi via Ethernet as this will serve to be the network connection to the RPi while it is on the bench.  While the test setup is on the bench, the MonoPrice Battery power will be supplied by a dual USB power supply and the iCreate Battery power will be supplied by a 6 volt power supply.

So what am I able to do with this setup?  I am able to build up to a final configuration over time.  The key elements are:
(1) implement a connection strategy between the RPi and some other controller over WiFi or Ethernet
(2) control of the pan/tilt servos via the SSC-32
(3) stream the camera to and through the RPi
(4) control the iCreate via a serial connection from the RPi
(5) interface a distance sensor to the RPi via the PiFace
(6) interface various digital pinouts on the iCreate DB25 connector via the PiFace/Protoboard
(7) Use either battery power or power supply to power up the equipment

I am hoping that I will be able to put together the test setup in a number of phases:

(1) System on bench / ethernet connection:
a. build up a Lexan plate with holes drilled for the iCreate body, mounting for the RPi, mounting for the SSC-32, mounting for hub / batteries, and mounting for a pan/tilt unit for the camera.
b. mount plate on the wood platform via standoffs with the rest screwed into the plate.
c. build up pan/tilt unit, interface pan/tilt to SSC-32, test with RPi.
d. connect camera into system, test with RPi
e. connect RPi over the network via ethernet, stream video over ethernet
(2) System mounted on iCreate / power from bench(3) System mounted on iCreate, all connections independent of bench