ok, honey. the best thing for you to do would to buy a book called The Conscientious Marine Aquarist by robert fenner. This book will tell you everything you need to know about setting up and maintaining your tank. I've been doing this for 2 years, and i still refer to mine, so it's a great investment.
Now, that sounds like a great deal for you water, cause i buy mine for $0.64 unmixed at walmart.
I didn't see anywhere that you had any powerheads, so if you don't have them, you should get a few. for 180 gallon tank, i'd get four powerful ones. These will circulate your water.
While your tank is cycling, you should only do water changes if your ammonia gets above 1.0. This is JMO, and you will hear other opinions. This way, your hitchikers have a much better chance of surviving, and your tank still cycles thoroughly. Other than that, you don't have to worry about doing water changes to remove nitrates until your cycle is complete. You'll know your cycle is complete when you have 0 ammonia and 0 nitrates.
you don't need to have your lights on for the rock.
ok... here goes. the LR from your LFS can either be "cured" or "uncured". cured refers to LR that has no die-off on it at all... there is nothing dead on it. uncured refers to LR that is live, but has some dead stuff on it due to shipping or whatnot. Anytime you introduce something dead in your tank, it's going to introduce ammonia. the main way to tell the difference is to smell the LR, if it smells absolutely wretched, that means it's uncured. if it just smells like ocean, but not horrible, it's most likely cured.
To start your cycle you need to introduce ammonia to your tank. If you're buying cured LR, you'll have to introduce ammonia another way. If your LR is uncured. all you have to do is put the LR in and let your tank cycle.
If you don't see ammonia in your tank a few days after adding the LR, it's most likely cured, and you'll need to manually introduce ammonia. The best way to do this is to buy a couple of raw shrimp from your grocery store. Put them in a mesh bag (you can get filter media bags at your lfs for this purpose) and throw them in the tank for a few days until you see about 1.0ppm ammonia in your test. Then remove the shrimp. This is the beginning of the cycle. After this, you'll wanna test your tank about every 3 or 4 days. once you see ammonia and nitrites at 0, and nitrates at more than 0, you're finished cycling. Then you'll do a water change to get rid of your nitrates, and a few days later you can add fish.
jeeze, there's so much information to go over... you must buy that book! it's a necessity!!!