But salt would be good for the pond I heard? All of the plants died? The fish suffered and died? That's just amazing who would have thunk?

Check your PH. Some plants are a bit resistant to high salinity. Don't taste the water, but after time with water exchange it may have dissipated, but just like with the old style evap ponds, usually salt is all that is left. I would put some test fish in, after very thorough water tests. Or get tilapia.