As for the -1 and -2, I am guessing that he is referring to adjustment for reciprocity failure. If you did not adjust for that, you will likely have severely underexposed negatives, especially with Tri-X. The tabular type films, such as Acros, T-Max and Delta, tend to do somewhat better with reciprocity failure. From the specs provided by the manufacturers, Acros would appear to be the champion in that regard.
Nope, you'd *add* exposure time to correct for reciprocity failure. Agree with you about the uncannily good reciprocity characteristics of Acros, though. Even if he isn't a tabular grain film.