I think the cables are fairly specific, sadly. I tried my old Carsoft cable with INPA and it didn't work. I have the Carly cable for Carly and the VAG cable with pins 7 & 8 shorted for INPA. With Carly and that age I think you need the cable rather than the bluetooth adapter: either way it's likely to be more reliable anyway, to be honest.

Re: Bentley, yes, worth every penny. No idea what the oil burners do for a manual, the Bentley only covers petrol cars because it's American.

The SatNav sounds a bit bodged, to be honest. There are all sorts of wierd and wonderful replacment head units running Android/Windows with what is probably massively better navigation and bluetooth phones than the 15 year old BMW unit, I think I wish I had gone down that route before fitting a wired-in Parrot kit for the phone and replacing my old CD NAV and 4:3 head unit with DVD and 16:9, but it's too late for that now! But if you're starting from a clean slate with bits not working you might like to look for alternatives to the whole BMW set-up...?