Chris,
I really don't know much about the details of B52 design. I am going from this extract taken from the B52 history site:
An unusual feature of the B-52 was the use of a pneumatic system as the primary power source in the operation of all auxiliary functions aboard the aircraft. High pressure, high temperature air was bled from the second stage compressor of each jet engine, and carried by ducts to the desired locality in the aircraft where it was transformed into electrical or hydraulic energy by air turbine-driven power packs. There were ten turbine-driven hydraulic pumps which supplied pressure at 3000 pounds per square inch to drive the brakes, steering mechanism, spoilers, bomb bay doors, and the adjustable stabilizer. The pneumatic system also drove air turbine alternators which provided the electrical power for the aircraft.
That suggests to me that they may have retained roll and pitch controls - I note that there is no mention of a power pack supplying hydraulics to the rudder, but as I said, I am looking for confirmation. This in contradistinction to the A300 which would definitely have been without any form of control.
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.
Bottom line is that the B52 survived, so it must be possible in at least one case.