What kind of corals are you getting?
You do not need to add calcium to your system.
Depending on the corals you get you may need to attach them to the rock either with an epoxy or superglue gel. again depending on the corals
Anemones and corals don't mix well but that's only if they touch. The anemone is going to win every time. If your anemone has stayed put I would say you will be fine placing your corals.
Nitrates - 20 or less Less is always better here
Good flow and good lighting are also key