Everything should be quarantined and your bucket idea is a good one. Though, if you QT
it in a tank, if you have a spare one, you can watch for bad things like aptasia and other undesirable hitchhikers. QT
'ing it gives you the opportunity to remove the unwanteds a bit easier than trying to chase things down in your main tank. Ad a heater and powerhead and give it a few days. Then test the water. If it is stable, then you can add the rock to your main. If not, then you can either let it cycle out or do water changes for a few days/weeks til the rock is cured and safe to add to your tank. Salinity should be between 1.023-1.026. I don't know what the exact numbers should be and really, but I wouldn't worry about a few (3) ppm
's. That's just me though. Others may have a different opinion on that.