Good suggestion alarm, but not all of us are as good as you are (thanks for some nice tips by the way). Having cut my teeth on changing panels, it's sometimes easier to correct an existing system - just do it one stage at a time though. I don't know much about the accenta 6, but most of the accenta RKPs should work, but as always, you'll need the manual first to show you the connections required - ask tech support for a copy at the honeywell website, but basically, its a case of connecting like for like between the panel and the keypay using 6 core cable.
Mike T
December 2011