Chance is not a natural law, by natural law I'm refering to chemical ones, where if you combine Hydrogen and Oxygen at a ration of roughly 2 to 1 and add energy you'd get water (essentially the result you get from burning Hydrogen I think). You seem to think that such laws wouldn't produce lots of repitition. Just look at the many Hydrocarbons out there. You consistently get repeating patterns, whether PVC or Stryofoam, the chemical pattern is repeated again and again in linked chains.
In Referance to Evolution (and I won't go into Gradual or punctual, even though that goes down a very interesting argument), I don't think Macroevolution works at all. Microevolution does. To explain better Macroevolution is in referance to evolution from one species to another species, and (at least for me) a species is defined as a group of living beings that is isolated reproductively because of a biologic difference from other such groups. This includes two species which can produce offspring, but the resulting offspring isn't reproductively viable (in other words, sterile). Microevolution on the other hand is variations within a species (ie. I have brown hair but someone else has blonde hair).
Evolution is supposed to be driven by mutations, which are essentially driven by chance. Chance encounter with something which would cause such a mutation and the chance that it would result in a positive change. Most if not all documented Mutations have a negative effect on the carrier. Cancer is a prime example. Sickled Cell disease (a mutated genetic disease) could be concidered to have a positive effect for a carrier of the recessive gene. Sickled cell disease is deadly and painful for those with the gene "ss" where "s" is the Sickled cell gene and resessive and "S" is a normal gene. However, someone with "Ss" is just a carrier but not a sufferer and carriers are immune to malaria (that or some other tropical disease). However, the fact remains that the mutation is harmful to those who inherite both of the recessive sickled cell genes and essentially negative effects for the gene poll as a whole because two "Ss" people theoretically have a 1/4 chance of any one of their children inheriting both genes.
Bactierial mutations against antibiotics are another potential exception, however a closer examination shows that such mutations tend to result in a loss of information and/or hurt the bacteria in some way because either they have lossed a certian ability, or the additional immunity creates adverse sideffects in of itself.
For evolution a mutation has to both be benificial and add information. Most or all recorded mutations have had negative effects, and the best candidates for benificial (the bacteria) lose information and/or experience negative side effects.
Sorry if I lose anyone, please ask if any specifics need to be explained.