James

The DNA 200 communicates over USB HID, as well as supplying a standard USB CDC serial port (/dev/ttyACM0 on Linux). We intentionally chose standard protocols so as to not require drivers on less common platforms. If you want to get it running on Wine, you'll want to contribute USB HID support to that project. Wine has needed that for a while -- it could use Dymo scales, many embedded programming tools, etc. if it had it. I don't think it would be a very large project, as the kernel hidraw is very similar to Windows's HID.

The reason for an accessory board is to provide reverse voltage protection for each cell. Otherwise you could damage your board and/or batteries in the event you put one in backwards.

Set Display->Battery Meter to On All Screens to display it on top of your custom screen.

I should add that while the Windows serial driver is proprietary, the protocol it speaks is standard USB CDC serial. So Linux will recognize it without a driver. Because the device is composite, the CDC serial must have an Interface Association Descriptor, which makes the serial not work with Mac OS X (no IAD support). But, the HID-tunneled serial will work on every platform.