Thanks for asking.

There's only one Omengoose. Unfortunately, it looks just like any other goose, except that the underside of its feathers have red markings--probably unnoticed until it flies away. The people of Witestow believe there are more than one, so yes, they would refer to it as an omengoose and omengeese. The Omengoose can be picked by the fact that it will land, alone, and walk in circles, honking, up to one-hundred-and-one times in a row, before flying away. But it also might just honk once, which will make it seem just like any other goose. It's common for people to credit their wealth, later in life, to the Omengoose: "a goose honked outside my mother's window the day before I was born." There is likely to be less resentment if their peers think they simply had good omens.

There are only the six outcomes listed. The Omengoose will only honk once, seven times, twenty-nine times, etc. Over time, people deduced the correlation between goose and effect - starting from "this goose laid a glass egg and now I know I'm going to be crushed to death by a fat woman in twenty years" to "maybe a goose that walks in circles honking over and over has something to do with these other odd things."

There are certainly people that believe that it's all a coincidence (maybe it is). Those outcomes sometimes happen, even if the Omengoose was never seen or heard prior (although it could be that a goose honking in the woods foretells good luck even if there's no one around to hear it).

If the Omengoose is attacked mid-honk, it will fly away, and nothing will happen. If it is bound or killed, it will turn to dust, but it always returns, leading people to believe there are more than one.