The property address is most important and would definitely use that in the title. You'll find the MLS # to be almost as important. Why not include both in the title? Then reverse the order for H1?
I wouldn't be too concerned about duplicate content. I'm not sure about your area but most areas have an MLS that is syndicating the listings to hundreds, if not thousands, of sites which all use the same description.
In working with real estate sites I also found that "house for sale on {street name}" or "home for sale on {street name}" tended to drive traffic to the the individual property pages.
What are you doing with the property photos? I'd optimize those as well for the property address and MLS number.
