HD:
Not sure what you're trying to achieve by adding sultanas to the bottles. I think some recipes call for sultanas to be added as a source of yeast for fermentation. Given that primary fermentation has already occurred, I'm not sure what that's going to add. I'm not sure how wild/predictable/flavoursome the yeasts growing on sultanas are - I've never used them in this way. I guess as you seem to be conducting a decent experiment with control groups, you can always let us know how it goes.
Bum:
Non-boiled ginger is potentially risky, I agree, but I am experimenting, and finding ways to reduce that risk. I feel it's worth the risk to try and extract a spicier ginger flavour from the same/lesser quantity of ginger, cooking it kills off a lot of the flavour. The most important part is that I start off the ferment with cooked ginger, and only add non-cooked ginger once fermentation is well and truly under way. Ginger will be well and truly peeled to remove most of the nasties living on the skin. I'll also have to look into drying out fresh ginger root - or finding somewhere I can buy it.
I do believe I've read somewhere that ginger has both antibacterial and antifungal qualities, so it's use raw may not be as dangerous as most ingredients would be. Maybe I'm wrong, maybe I'll be proved wrong. Only time [and experimentation] will tell.