First of all, of course, congrats for your promising results, and thanks for sharing them with us.
I would like to comment on a few things in your setup:
- your Ferricyanide bleach seemed to have caused trouble, and the C41 process is not even rated for Ferricyanide bleach (but that's most likely not the cause of these spots). If you can, try to get Ammonium Ferric EDTA or even better, Ammonium Ferric PDTA to make a real C41 bleach. PhotoEngineer has posted a few recipes here on APUG. One big disadvantage of your Ferricyanide bleach is that the Ferricyanide will eventually (within weeks) kill the Thiocyanate and this will render your bleach green, and what's more important, ineffective.
- C41 needs a very strong fixer and simply substituting Sodium Thiosulfate for Ammonium Thiosulfate will likely lead to retained Silver. If you really can't get Ammonium Thiosulfate from anywhere in Australia (which I think a bit hard to believe, given that you did get CD4, HAS and the other stuff), you should at least add Ammonium Chloride to your fixer recipe to boost it a bit. There's a formula posted by Ole here, you will have to adjust pH of this brew to reach the pH 6.5 needed by C41. I recommend you skip the Metaborate and use Sodium Metabisulfite to lower pH to 6.5.