Yes, stairs from first floor to fourth are wood. Garage to first are concrete.
Windows on the Green has a flat roof, so they obviously wouldn't use shingles. Probably use a waterproof membrane or asphalt[tar]. This definitely requires maintenance, just like a sloped roof w/ shingles. I agree the flat roof looks better, and lasts longer...but I believe it's more expensive and more likely to leak. Depending on what shingles were used for Park 570, they should last at least 15 years.
Also Windows on the Green is wood-constructed, like Park 570.