OBDeleven Function

OBD11 has options for the first three areas above (and more) whenever a particular module is selected and it's likely that you will spend 99% of your time in these areas.

Changing the values in area 4 above is generally more rare because it means that you need to identify the memory address in module's "operating system" that you want to alter and you need to understand (at least in part) the programming routines that the module uses (which isn't normally in the public domain).  This is the area that EEPROM accesses.

If you are just starting your OBD11 journey, my hunch is that it will be extremely unlikely that you will use EEPROM.

Question 2:

Control modules that were produced by the VAG group up until 2020 used Security Codes to limit access to various components (but not all) of the first 3 x areas above. These were a 5 x digit number. As of 2020 –beginning with the market entry of the MQB37W (Golf 8) - The VAG group introduced the SFD (Schutz Fahrzeug Diagnose) procedure. It is likely that your ID4 will use SFD if it has a MQB-evo build platform.

Question 3

Not sure about Chinese ID4 - but almost certainly, retrofitting ACC will be what's called "Software As Product" (SWAP) which means that you will need to buy an authorization code that's tailored to the car's VIN from VW. Also, ACC needs a forward facing radar module to operate- does this car have this module?

Don