I know about the stalk control adpators, no one makes anything to use the standrad display. If you use a different head unit you get just the date up in the display. I like to see the info in big fat letters as I am so used to it.
I did have a kenwood unit with steering remote in an Astra SRI, but could not get on with not having the display working.
If I remember right you used to be able to get amps that would take a low level input, like direct from the speaker output on the headunit. Can you still use this method?