Hi Karl,
After watching your videos, I realize that I should have told you that the only thing I control in the XPDR is the digits by rotary encoder as you did in one of your videos. Sorry, I missed that your original post talked about programming the XPDR by pushing the 8 buttons. I am not aware of how that would be done.
Arduinos looks like a lot of fun to play with but that level of engineering is too heavy duty for me.
Have fun,
Rod