@Mutley - can you let us know how you get on please? Interested in Carista for doing the exact same modifications and don't have any need/desire to go OBD and Android as on iOS stuff here.
I'm especially interested with the Stop/Start voltage thing - do you get the dash message every time that the stop start would have worked throughout a journey, or does it only flag once at the first? Cheers, hope this makes sense.