Me personally, I wouldnt add sea water even though I live in flordia and its readily available. You just dont know whats in it.
As far as rock curing, I would say a few days separate from the tank and livestock should be enough to make sure it doesnt spike. You can use a rubbermaid container with a powerhead and heater in it.
I'm also usually overly cautious though so some people may have tried other methods sucessfully too. each tank and each situation is different.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.