Can't help you with the Kahlgren property location, although I'm sure someone from Sabula will chime in with more info.
As for DuBois' history, it evolved into the social and economic center of the area. As people becam more mobile they seemed to travel to DuBois for their shopping, drinking and dining activities. That still remains true today, maybe to a somewhat lesser extent, since other areas have grown in their offerings of alternative choices.
It has always been somewhat confusing to me when I look around the area and see the lack of restaurants in many surrounding communities where we have an abundance of them. Many of which are frequented by people from 30-40 miles away on a regular basis. I suspect that I-80 has helped that in the more recent years, but that still doesn't explain towns like St Marys, Ridgway and Brockway where there is a distinct local support thinking and restaurants seem to struggle to stay in business.