You didn't read linux-usb-cgminer ...
Nope. Unfortunately I didn't know about it yesterday, and besides, this particular mining rig will have to host other applications too, so perhaps a standard Debian is better for it too.
Thanks for pointing it out, however -- on the next machine which is basically nothing but a PSU, mainboard and 5850 GPU (once I get a spare 5850), I'll definitely try this approach, a bootable USB stick sounds like a sensible way to reduce power consumption.

I meant it has all the info needed to install cgminer on USB or HDD with an older OS (Xubuntu 11.04)
Looking through there would have answered your problem about SSH since it is in there also.