1) "Exit navigation" I think is #7.
2) Try them out.... most of the reply commands are for MM. The POIs are for iGudiance/Routis.
3) Try them out... easy way: don't have RR running and say the command and see if gives u a message box.
4) Destination home is a favorties command. The config program can configure it, but you'll have to edit the XML file. Play, stop are hardcoded. I wanted to add scrollup/down but its not in the SDK.