I don't thing a deck count would mean very much. Remember that only the rotating section has gravity and there would be two sets of decks, one in each half of the centrifuge and probably with some of the "outer" edges kinked or slanted around the central bearing. The rest of the ship would be laid out in a fashion to accommodate operating in zero-g so it'd probably have sectors and subsections rather than linearly stacked decks. Even so it'd be mostly, zero-g cargo, engineering and docking areas.
As for the crew capacity, it runs from the Cerberus's 348 (mentioned in "The Needs of Earth") to the Roanoke's 547 (mentioned in "Intersections in Real Time") and the "1000 crew a piece" fleet of Omegas in "Endgame". One might argue that the disparity could be down to the Roanoke and the fleet at Mars having large Marine contingents for boarding operations, but that's just speculation. If that was the case then the Mars fleet would have had about 15,000 Marines, while the first wave in "Severed Dreams" (assuming the Agrippa had a similar compliment) would have only had 400 or so plus however many were in that breaching pod.
