On average, listings lease in the $20's per square foot per year. The Newtown region is going through a a rise in rates. In the last 3 months, the median rate increased $24 per sqft per year.
Compared to the rest of the Fairfield market, the Newtown submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 2 listings have been posted online, which means spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 150% of the available space in the Newtown are subleases, so you might be able to snag a great spot on a short term. 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 1,900 sqft. Most buildings in this market are around 2 floors. Most buildings in this area were built in 1973 and are Class A.