COOL, thanks for the schematic! May sound silly but that really helps, simple as it is.
As for the ALDL data exchange, what I mean is, it's not really so much an "exchange" as much as a simplex data stream that goes on even with nothing plugged in to interact with the computer (as long as that 10k resistor is installed in the "A-B" positions to tell it to start spewing). So there's no data the Arduino needs to send back, it just needs to listen
Think I've got all the info I need to get started, at least until I get my Arduino board back. Thanks!!