Has anybody used those Bugpack bushings on their front beam? What are they like ? Do they replace the needle bearings and bushes? ie. remove all bearings and bushes and replace with the urethane insert that slides into the front beam tubes, is this correct?

Yes, they replace the inner and outer bearings in the beam.
Mixed reports on them, but I think they are fine, though need to be chaged a lot more than the factory bearings do....
and need to keep them greased, or drill the holes through where the grease nipples are and use a urethane friendly grease on the arms.