If it's the same sort of "energy" that allowed Spock to learn of the death of the Intrepid
crew in "Immunity Syndrome", then the answer must be 1) very high FTL speed, but 2) unknown, but range is counted in lightyears when source is intense emotions from hundreds of people.
Supposedly, Spock was able to identify the source as being that of the dying Vulcans; he also managed to get some of the contents. (Deanna Troi's abilities might be inherently much more limited, while Lwaxana Troi might have even greater abilities than Spock.) No indication that he could do any sort of direction-finding or range-finding, though.