Crushed corals IS aragonite - only difference between the 2 types mentioned is the size of the grain. Aragonite is a good PH buffer.
Saltwater basics - Test kit - Ammonia 0, Nitrite 0, Nitrate 20 ppm or lower for fish, 5ppm or less for hard corals, PH 8.2- 8.6. Hydrometer - readings 1.020 to 1.025 for Fish, 1.024-1.026 hard corals + clams. Test your own water, be in control, and if possible use only R/O DI water to aviod problems related to poor water conditions and high levels of dissolved organic matter. Top off once or twice a day with freshwater, salt does not evaporate. Water changes of 10-20 % weekly with pre heated, pre mixed and matched saltwater. You'll also need a heater in the main tank 86 degrees is a good temp - helps with both PH and salinity stability.
Organic Filtration - Live rock and substrates are your Bio-filters. Cure all LR to aviod deadly hitchikers. Use sterile sand or aragonite not someone elses. Marine Ick and other deadly organisms have a sandbed stage and just because their fish show no signs doesn't mean it's not there. Water movement over the rocks is important- get 2 good quality powerheads facing each other with a gph of 10x your tank volume minimum. HOB filters are a waste of electricity - get a small HOB skimmer, they are built to handle the abrasive nature of SW. The 2 powerheads also keep SW compounds from falling from suspension. You can use the curing process of LR to cycle your tank - research it, this can take up to 10 weeks but is by far worth it in the long run.
Lighting - Fish only irrelevant, corals and clams - resarch the thier watts per gal and gph flow.
UV sterilzer - your goal is an eco-complete system. UV will kill algae spores + disease juviniles but it also kills planktonic larva as well as Micro and macro fawna + flora babies/spores - it's a trade off. Not using one is more benificial in the long run.
Salt mix - for fish only use a saltmix lower in Cal, Mag,+Alk , for corals use Reef mixes but start with the mixes lower in Cal, Mag,+Alk.
Take it Slow! - do your research 1st - and most of all enjoy!