Not sure I completely understand your intended layout, but, keep in mind that your Kapex will benefit greatly by being serviced with the shortest length of hose possible. Also, use the D36 hose for the Kapex -- that offers better air flow than that of a smaller diameter hose, yet better flexibility than that of a larger diameter hose. I just don't think the Kapex is a tool you want to use in conjunction with a boom arm. So, you may wish to reconsider your layout, or plan on moving the extractor as needed.
As for your other extraction needs, I think all other tool usage could benefit from a boom arm to get the hose up off of the floor and out of your way.
Have you considered the issue of static buildup? If you are using a Festool extractor, you will want to consider this, especially if you also plan to incorporate some PVC and/or a cyclone in the mix which would break the otherwise continuous path to ground. Wouldn't want to blow a circuit board in the extractor.