incredibly nifty project...
regarding power supply: i don't understand why you bought eight of the canon power adapters... it's trivial to build one yourself (especially for somebody who has the metal-working resources to craft those disks for mounting!):
http://chdk.setepontos.com/?topic=6089.msg64166#msg64166and secondly, chdk now has some support for remote-control via ptp (usb picture transfer protocol), while it was not ported to your camera yet, that would give you a neato solution for both remote-configuring/firing the cameras AND retrieving the pictures without the tedious sd-card removing...
(and if you are soldering stufff to the camera anyway, for the power switches, you could just hook up the camera's uarts (serial ports) for remote control aswell.)