Artificial gravity is possible. Find any rock, for instance. For gravity plating, find a flat rock. Gravity shielding is not possible unless you can produce negative-mass matter (which is not antimatter) because you could then violate Gauss' law for gravity. However, in order to produce gravity shielding, you would need exactly as much negative mass as you have positive mass in order for the two to appear as zero mass outside of the near field. The principle problem with artificial gravity has always been that of mass density: to make 1g of gravitation field, you would need 1 Earth worth of mass. Even with neutron degenerate matter, you would need a few thousand cubic meters of it to come up with that much mass. The only stuff that has the proper density is a singularity. And if you were generating singularities a few meters away, spaghettification and tidal effects would be difficult to avoid.
The key problem with the whole "suspend thing that goes in circles in a gravity well but is held up by magnetic field" is that it can work with a perfect vacuum, no friction, and no domain change losses... but there would be no way to extract energy from it. Sure, it's going round and round, but how do you get it to DO anything?