I don't think cantorian concepts of various infinities are really helpful here Rev!
Principly this is because we are considering an "interpretation" of quantum theory.
Quantum theory gives us an excellent way of predicting the probability of an outcome but doesn't really give us an explanation of the "mechanics" of what causes that outcome.
Quantum theory interpretations attempt to do this and the "Many worlds" interpretation is just one of many. All are mathematically consistant and none provides any way of testing whether it is correct or not.
So IMHO all are equally useless (but then I come from an experimental background)
However let's indulge the theorists.
The idea is that a universe splits whenever there are multiple outcomes of a quantum event. So we need to consider whether that just means that all universes are exactly alike with only differences at the microscopic level or whether these quantum events can influence macroscopic events like which lottery balls fall oout.
For this we need to consider non-linear dynamics or Chaos theory to it's mates.
Certain systems show very great sesitivity to intial starting conditions. The double pendulum is the classic example
http://www.met.rdg.ac.uk/~ross/Documents/Schoo lTalkDP.html
in this animation there is only a tiny difference in the initial speed and rapidly the motion becomes very different.
Indeed to predict the outcome of this or the lottery machines you would need to know the starting conditions with infinite accuracy.
ctd.