Uhm, no they don't. It is mostly private land. That is why they have been drilling it extensively for years. They have made North Dakota the 2nd largest oil producing state (after Texas).
Known Bakken oil reserves is not something new.
No, but the combined technology of hydraulic fracturing with steerable horizontal drilling and 3D seismic to track the lateral placement is relatively new. Until this century, it wasn't economic to produce these tight formations. Hydraulic Fracturing began back in 1947, but without the other two, it was not economic enough to attract the investment we have seen over the last decade.