| Everything you outlined is exactly correct, and I see you noted this is not a residential service, and your wire sizes are correct.
I have a few questions and comments:
What is the distance of the interior portion of the 200 amp feeders from the trough to disconnects? This distance of interior service lateral must be kept short as possible, most inspectors and utilities allow up to 10 feet, but only if adequately protected.
If the grounding electrode conductor only connects to ground rod(s), then #6 copper wire is allowed, NEC 250.66(A). This can be run in PVC conduit from the point of connection to the grounded conductor (neutral). This connection can be at the connection of all the neutrals in the trough, or in the meter if allowed by utility or local code.
Also, since the building is all metal, it must be considered as a grounding electrode, here is where you must use #1/0 copper. Again this can be run in PVC conduit where exposed, usually the entire length if exposed in an open steel building. If a steel I-beam is close to the point of connection to Neutral, can be open wire tyrap or strap as needed.
From the two main breakers, the feeder now must have an equipment grounding conductor, if pulled in conduit, use green #6 for both feeders along with the two hots and one neutral. Keep the connections of both separate in the panels.
If the water is utility with metal pipe, then it also must be considered as a grounding electrode no than 5 feet in from the street, and need #1/0 connected to it, jump out the water meter with the ground wire. If the water is metal and well, bond it the the equipment ground from a panel to anywhere on a cold water pipe.
The feeder for the apartment may be #2/0 since it is residential.
That's all I can offer for the moment, hope it helps. | 
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