Your gonna find the joy of discovering little things in your tank. In order to have established bacteria sufficient to handle fish loads, feeding, and ammonia sources, yhour' gonna need a LOT more live rock for it to live on.
If I were you, I'd get a 20g tank, HOB
skimmer, basic flourescent light, and a small heater. Put the damsels and the rock in it. No sand or cc. Kids can still enjoy it and discover.
Then remove the crushed coral, rinse, rinse, and rinse some more the new dry aragonite sand for the big tank. Get some base rock, and some more live rock - uncured. Then fix all those things you learned when you first set the tank up and said, "hmmmm, I coulda done that better".
Now, with that base rock and new uncured live rock, take your time to aquascape/stak it and monitor the ammonia. Add shrimp IF needed.
Now you got a good cyle with sufficient rock (100 to 150 lbs total) to handle a large tank fish bio-load. You got a QT tank to introduce new fish and ensure their health before they go in the main - where you'll never catch them by the way, as they infect and kill others.
Read article at this site on Quarantine tank (QT) setup.
Take the QT down easily after you're fully stocked and set it back up as/if needed to QT new fish or treat fish from the main with medications your main tank won't do well in.
Sorry.... I got a little winded.
P.S. - you going fish only or reef?