Hi Steven,
I am no mariner, but Leslie Reade compiled a list of all the crew from the Official Log and added to in some respects by other information.
There were only 6 of the crew (of 52 according to Reade's list) who were (as far as I can see) assigned to passenger duties. The Chief Steward William Hughes also looked after Captain Lord, a Second and Third Steward, a Mess Room Steward (for the crew but also probably doubling up), and 2 ship's cooks.
All the passenger accommodation was originally designated as 'State Rooms' as per Harland's article and the original plans that survive, and was above the main deck.
Passenger accommodation would have been strictly out of bounds for the crew. Ernest Gill and his cabin mate William Thomas were certainly in their original cabin below decks as per William Thomas's USA press interview. Groves clearly had his usual cabin which was diagonally opposite that of Stone, as he described certain things in the late 1950s to Walter Lord that rules out a change of berth.
What is known is that The Californian had a very easy crossing of The Atlantic to Boston till the 15th, in very fair weather, and I should imagine that the lack of passengers that crossing meant the food for the crew was probably better, and with better service, as the ships' cooks and Stewards had nothing else to do.
Cheers,
Julian