I know that Flight of Fear opened up in 1996 at PKI, but were any others built before it?
dont think so.
Are you considering S:TE at SFMM to be a magnet-propelled coaster? If so, wasn't that built before FoF? But I do believe that FoF was the first full circuit magnet propelled coaster.
Just to confirm, Flight of Fears at PKD and PKI both opened in 1996. Superman: The Escape opened in 1997.
------------- Gravity is your friend while riding a coaster. Your enemy when you trip and fall off a cliff.
The first use of magnets however was on Disneyland's Space Mtn and Big Thunder Mtn in Disneyworld. They are used in the station areas to "push" the trains to the next braking zone.