Zillion is not a specific number. It is just an expression of a very large amount.
No. It is an expression to indicate a very large number.
Zillion is not a number, along with Ba-zillion and Ga-zillion (which would be cool though) Zillion is really used as "slang" indicating an infinite or very large amount. A extremely large yet...
999 zillion and 1
Zillion is not a proper number: it is used to signify a very large, but unspecified amount.