Hi if you look at the transponder in the duff key you should be able to buy a replacement on the internet, replacing this should not affect the keys functions as the PCB is original and the transponder only communicates with the pick up ring inside the ignition barrel.
Steve.
Hi if you have the headlamp switch set to Auto and are trying this in daylight they won't come on, try it in the dark with the switch set to auto, as for the SD card try eBay but it will need to be paired with the head unit.
Steve.
I'm pretty sure your stuck with the screens.
Firmware updates normally fix bugs and are sometimes needed in order to ensure that later version maps work.
Have a look on this link it might help
https://mca.electricmura.ro/en/blog-audi-mmi-mib-models/