If you yourself are uncertain as to how to proceed I would strongly advise that you engage the services of a consultant / mentor / coach. Merely championing ArchiCAD in the office will not suffice here.
With the aid of a consultant you might establish (among other things):
team member roles and an on-the-ground plan of attack
parceling out of the work to team members or sub-teams
keeping as many hands out of the Teamwork model as possible
protocols for information (used to be called DWG compatibility in the old days) sharing, project libraries, schedules, document frameworks.
DWG production can mean a number of things these days. Round trip collaboration with consultants using DWG may have issues that do not have anything in common with the challenge of producing As-Builts to a client's CAD standard. The first is all about interoperability; the second, if well organized, is housekeeping. [there's lots of resources available to do the hand-off of the deliverables]
The point of working in ArchiCAD would be the right and proper establishment of Information standards. Information is key here.
[note the absence of the term BIM here, but wouldn't that be what you want to do on a project this size?]
Think Like a Spec Writer
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