AltairClone.com

There's room enough in the Clone case to add a second 9-slot board (oddly enough, there's not enough room for one 18-slot board!)
If I do add it, do I have to run power wires to the new board or does the connecting ribbon cable take care of that?

You should probably take a look at the board and/or get out a meter and see if the power pins on the buss are even brought out to the board-to-board connectors.
However, for better power distribution, I'd run a new set of wires from the power supply to the power connections on the 2nd board no matter what.

Mike