Josh, I briefly described cycling in my second post in this thread. Basically, your fish produce ammonia. ammonia kills fish. so, you need some way to get rid of ammo. bacteria are your solution. given time, bacteria will grow that eat ammo and turn it into nitrites. however, nitrites also kill fish. fortunately, given more time, different bacteria will grow that turn nitrites into nitrates. nitrates can also kill fish, but at much higher levels than the other 2. Cycling a tank is this process of building up a base of bacteria that can handle converting the ammonia in your tank into much less toxic chemicals. a tank is done cycling when your ammo levels drop to 0 and your nitrite levels drop to 0. notice i say "drop" to zero. as in, you did have it but now you don't. a tank that has never had ammonia in it will never cycle. so don't fill up your tank, read the tests and think that since there is no ammo and nitrites that you have finished cycling. Cycling can be done in a few weeks or may take over a month.
New, as to your additive, give it a try, it won't hurt. however, it probably won't speed up your cycling very much either.
Live rock and sand are rocks/sand that have sat in an ocean reef and so have been filled with various animals and algaes. they also contain the bacteria that are needed to cycle a tank. they are called live because they contain live animals, from bacteria, to algae, to corals, to invertebrates. IMO, LR is one of the most fun things of this hobby, you never know what is going to crawl out of your LR.
HTH kris