Please see link for the concourse layout.
http://www.100asw.com/building/plans-and-specs/
The EY Tower will connect day 1 to the PATH. When you go north into the Richmond Adelaide Centre it will be an immediate right (before the drug store).
They are not planning to have a connection to the residential building (yet). There is a provision to have a PATH connection along Adelaide (towards the small building with the Timmies on the main floor) but not towards the residential one. I'm guessing the residential will connect north since the other buildings in the Richmond Adelaide complex are older and probably not built with future PATH connections in mind (?)
I don't think Bell will/can move its equipment in the building east of the Timmies building so I'm guessing there will be no future development there.