I have been to the Gurney's nursery in South Dakota, and if you buy something from that location, it will definately be zone 4 tolerant. But Gurney's tends to sell the best tasting fruits not necessarily the easiest or most disease resistant. Trees on dwarfing rootstock tend to not be as strong. They often die after 10-15 years. An alternate choice is St. Lawrence nursery in New York. They will sell more disease resistant trees and vigorous rootstock. Taste is sometimes compromised for reliability. Just avoid the early blooming varieties unless you do not mind losing your crop most of the time. My favorites are Bali and Surefire.
On the Gurney site the cherry they are listing as their dwarf ' special ' is the Variety Carmen.
They say it will grow to 6.5 ft.
The only rootstock that could hold a cherry to that height as far as I know is Giselle 5.
I'm afraid that I cannot help as regards the zones. I've no idea what that means as regards temp.