Yes the critters bacteria and the algea will eventually colinate the rocks you have in the tank now. As for the ammount of rock you start with, depends on your budget. Most people say about 1.5 to 2 lbs per gallon of water when finished adding rock. It all depends on what you want your tank to look like.
Message to all aquariasts!!!!!
Anyone who lives within their means suffers from a lack of imagination.