1) The unit responsible for the CAS can avoid you like the plague if inside, or plan ahead in case you're likely to infringe (we can see which way you're tracking)
But they don't require 7700 for that, surely? I mean, if a CAS controller sees a 7000 squawk heading directly for his/her airspace, wouldn't he/she start planning for an infringement already?
2) D&D can speak to you whereever you are in the country, and the flashing emergency squawk will pinpoint you faster on their (and other) screens.
Does D&D have nationwide radar coverage? I though they did VDF triangulation?