I think you may be overthinking this.
For one thing sodium hydroxide is harmless, nothing to worry about. Caustic does not equal toxic.
Regarding the Pareth 25-9, at the rates we are using (low concentrations), and given the fact that there is very little residual left on the inside of carboys and bottles, there is nothing to worry about. Don't know if you realize or not, but betadine is registered for oral use (no swallowing, but is obviously not that dangerous).
If you want to use Starsan go for it (I do), but don't spend too much time worrying about the formulations of sanitation products.