I believe what they are saying towards the Data-to-Data on the 3 x lock is that there is no manual input to trigger it. Only reads it through the data of the car.
Sorry not to sure on what you are asking about on the Start / Ignition connections. I do see that the Gray feeds back the the Yellow/Red through a diode to prevent feedback?
Your shopping list is complete, you don't need a Smart start module. That is optional if you want to be able to start you car with your phone once you have installed the unit. ( Mind you there is subscription fees with smartstart)