A Slice of Life Park Slope Rental Woe

Here's an interesting rent-controlled Park Slope conundrum making the rounds via the Park Slope Parents Group. We post it because it raising interesting questions about what to do when the landlord starts doing ominous things in the building that indicate change may be afoot:

I live in a rent stabilized building. Recently the landlord has been demanding that he inspect everyone's apartment and when he comes he has come with 3 architects and they measure the whole apartment and take pictures while consulting a floor plan. Most of the tenants have complied because he has told them it is for insurance purposes and they are afraid to cause a problem. We have recently heard rumors that several of the buildings our landlord owns may either be up for sale (to Methodist Hospital potentially) or are slated for conversion to condos. Does anyone have any great resources as to tenants rights in this case--or perhaps even direct experience that would help us short cut the list of questions we have?

Evergreen Brooklyn rental questions.