The problem with blackout during a hot re-entry from orbit is plasma from the heatshield or tiles (in the case of the Shuttle) blocking radio signals at Mach 20 or so (about 6 km/second or thereabouts). This wasn't the case of the Falcon first stages as they were never going fast enough in the atmosphere to produce any plasma. If any of them had then the bottom of the stage would have melted since it's mostly lightweight low-melting-point alloys. Those sorts of temps would also have damaged a lot of the motors, the actuators, the guide fins etc.
As for the accuracy thing, again it was not a re-entry from orbit and the stage had guidance systems to bring it down to the barge, much as the Shuttle never had a problem finding the runway and painting the centreline during its landings. What puzzled me more was the speed at which the stage hit the barge. It should have been a lot slower, even with the failure of the guidance fins.