Your gonna want what's called a "galletto 1260" cable along with software called me7_95040.exe (link below)
True, but not required. ME7_95040 is Argdub's tool, and you can read AND write using it using a dumb KKL cable (cheap vag-com cable). No other cables are needed.
You read the file through the OBD port using the tool, it's really easy. Once it's read, edit it and save it.
Actually you cant write the 95040 threw the OBDII port BUT you can do it in what's called "boot mode", google it. it involves grounding out a pin inside the ecu.
You are writing the ECU through the OBD port, technically. Using a bootmode harness, you will place the ECU into bootmode by either grounding out a pin or using a resistor, depending on the type of ECU. Once it's in bootmode, you write your edited file back to the ECU using Argdub's tool (the same tool you used to read it) and using the same dumb KKL cable.