The B-2 is laterally unstable, so it must be assumed that the drag-rudders work automatically all the time in order to keep the nose pointing in the flight direction.
It's of course a FBW plane, so it is no bigger problem than for instance controlling the elevator on an F-16 fighter plane, which is unstable on the pitch axis.
In principle it has similarities to any FBW Airbus (320 and newer). A "bus driver" does in principle not touch the pedals until he has to land in sidewind. The rudder control is fully automatic even when the plane is flown manually on the sidestick. The computer keeps "the needle in the middle".
It's of course not the same thing since Airbusses are laterally stable. So the B-2 is a far more complicated thing in this respect.
The complications also show up on the price tag.
There is only one major advantage of "missing" vertical fins: Reduced radar signature.
An engine out situation is probably not the nicest thing to experience on a B-2, especially not at low speed where those drag-rudders will have very little effect. A three engine go-around may be a tricky thing involving the need for precise differential thrust. But well, with that price tag that could be automatic too.
Happy landing, Preben Norholm
Always keep your number of landings equal to your number of take-offs