BTDT .... and you're walking on thin ice, over quicksand.
First, off, make it clear that you're interested in bidding the job, but they don't even a rough guess without some committment on their part.
That committment can take two forms: Best is that they provide you with a set of plans, as close to what they plan to submit for permit as possible. You can review and act from there.
Less satisfactory is that they pay you for at least 1 day's work to research the design and develop your own set of sketches ... and a bid gased upon those sketches, with adjustments necessary as the plans are revised.
Less clear at this point is where the drama will go next. Here's my guess: your proposal will be too much, the general will say you don't know your business, and another contractor will be hired.
This other contractor will be carefully fed just enough information so as to avoid all the issues that you raised, and a permit will be applied for misrepresenting the intended use of the property. This will allow them to avoid any tenant-specific requirements, and pass on to the tenant the necessary changes.
Remember, the remodel is also likely to seriously affect the other trades as well - especially the plumbing and the HVAC.
Finally, be very wary of potential booby-traps. For example, the building may already have six meters, and no main disconnect. Oops. That's a major change right there. Likewise, the building's service may already ne maxed out; you'll want to look at far more than just the proposed remodel.
