Park1marine,
To Reef Central
Depending on the composition, your rock may or may not need any curing. If it hasn't been in an aquarium before, I would be worried about incompletely cured cement causing a pH spike, so you should monitor the alkalinity and pH to make sure it seems under control.
Flake food may not decay the way you would expect. The shrimp is a good idea. If you don't see an ammonia spike in the next few days, have your water checked with a different test kit.