Great info. You are certainly armed for bear!
Firmware is a special type of software used by the processor. Sounds like plan A would be to see if they can apply the firmware to your machine,
Plan B would be to see if they can get the organizer software using the part number above. You will still need embird for any alterations you make to the designs. Save them then use Organizer to send them to a floppy.
There were several versions of the D1 machine, with slightly different processors. Firmware is processor specific, so a D1 Firmware update may not be accepted if there's a mis match with the version of the processor in your machine.