The crushed coral thing depends on what your are going for. If you are trying to do a dsb I would advise you against crushed coral. If you are going for an inch or less sand layer and trying to keep it aerobic, then crushed coral wouldnt be an issue. Aragonite or calcium carbonate based sands will be enough to buffer calcium levels, and the crushed coral wouldnt be necessary.
Live sand is good for kick starting a cycle, so is seeding the tank with some live rock. Seachem stability might work, I like biospira, but its pricey at twenty bucks a bottle, so i might abandon the whole idea of bio additives and just use the live sand and go through a classic tank cycle.
