First...slow down and breathe a little
I know it can be confusing, but it sounds like your own track..
1st...power compacts are for corals. If you just want fish and LR
, normal output (N/O) lights will work just fine.
Salinity..or specific gravity. They both measure the same thing, just in different ways. Its like feet and meters. Salinity and SG
are both telling you how much salt is in the water. SG
meters are more accurate. Obviously since you are keeping saltwater fish..measuring the salt would be important.
Water parameters. You should have a test kit for all of the basic 4. Ammonia, Nitrites, Nitrates, and phosphates. Ammonia and trites are both toxic. After the cycle (wich can last 6-8weeks) they should read zero and stay there. Nitrates are bad, but not nessisarily toxic. Trates will cause problems with algae. The way to get them down range from simple water changes, DSB
, Caulerpa or macro algae..there are even some sponges out that will bring them down.
If your still cycling, you should be focuse on keeping the salinity in range...and doing water changes when the parameters get too high. Keep the water circulating and keep it heated. You will be fine.