In the last 90 days, 2 listings have been posted online, which means leases most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 50% of the available leases in the Forest Hills are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around sqft. Most properties in this area are approximately 2 floors. Most buildings in this region were built in 1940 and are Class B.