The 120-volt delta is for all 120-volt loads and I should have mentioned that I also have a 240-volt 3-phase delta for my larger loads (two services coming into the building)
I believe installing a 3-phase panel and install 2-pole circuit breakers for my lighting and receptacle loads is correct. The grounding (could be bonding) of metal raceways and devices will be connected to a grounding bar in the electrical panel with a #6 to the water service copper line.
Also I never want to see this again -
If you can, please get some pics of the transformer bank as well as the panel boards. It will make great tool for teaching code classes I will worship you
If you do go ahead with the additions yes, 2 pole breakers, and ground/bond as you would with a regular wye service including the 2 ground rods and water bond. Use white wire up to the lighting and outlet neutrals so it will be ready to change over down the road. Don't freak over it though. Most Norwegian factories have a 230 volt ungrounded service for lights and outlets plus another 690 volt ungrounded service for the motors and like. Ungrounded is the norm 120 volt hospital power in the United states and Canada. All working without issue.