lab sink, kitchenette sink and shower water calculation rate

The usage is driven by the FTE (from PIf3) numbers, so you need to be sure you have those correct. You 'll find that for "general office" space no transients are assumed, but you must make an educated guess at the number of visitors expected and include those numbers on WEp1 form, or it will be rejected by the USGBC during review.

By "cafeteria" do you mean an area where food will be prepared and served/sold to employees and visitors, or do you mean more of a breakroom situation? If part of the office building is designated as an operating cafeteria, you will need to identify that on the PIf3 form in Table 1 and Table 4. I would assume kitchenette sinks would have the same usage rate as kitchen sinks and you should only consider FTE, no transients. I'm a bit unclear about the lab sinks, what exactly will their purpose be?

Just to clarify further, do you mean “lab” as in laboratory sink or “lav” as in lavatory sinks (hand washing sink)? The reason this is important is “lab” sinks do not need to be considered in the water reduction calcs, however “lav” sink do.

Break room kitchen sinks would be accessible to all office workers, so basically you’ll need to assume 1 use per day per FTE
The “emergency shelter” sinks can be ignored, depending on your definition of emergency. If it‘s for use in case of, say, natural disaster, and not simply when the regular cafeteria is too busy, than it’s safe to ignore the water usage there. You should include a narrative explaining that the fixtures in this area are only for emergency use, and perhaps give examples of what would constitute an emergency.
The operating cafeteria is a bit more difficult. If the kitchen sink is equipped only with a commercial pre-rinse spray valve, then you merely need to show that the spray valve complies with ASME A112.18.1 standard of 1.6 gpm or less; it does not need to be included in the reduction calcs. If the sink is used primarily for filling pots, washing produces, etc., that’s all considered process water, which also does not need to be considered in the calculations. If the sink is there primarily for hand washing, then you need to make some educated guesses about the usage based the cafeteria’s hours of operation and number of staff working there. I haven’t found any USGBC guidelines regarding usage rates in these types of situations, but if someone else out there has, please jump in and correct me.