Spreadage is not in Wikipedia but is in an Urban dictionary.It is described as the point where two roads split.So,I'm going to have to say no,its not a real word in the strictest sense.
Coralline is dependent on light,calcium,magnesium and akalinity.It will vary between systems but usually a month or two after the cycle is a good time frame to see specks appear on the back glass and equipment.Compared to nuisance algae,they grow at snails pace in comparison.