What he says is more along the lines that we were supposed to be something closer to a shaman, he doesn't outright call us a shaman he just compares what we do to the closest thing he knows so if the herbalist's master were the one that's messing with the orcs and he said that he has an apprentice then the orcs would simply associate the herbalist to a starting shaman or something similar to that, regarding 2 I would think that at least our reputation around the area the informant is from would influence the informant perception of us when giving information, but the information itself looks pretty unbiased in stark contrast to to opinion the leader has of the herbalist based on the tribe attitude towards them, hence why I mentioned the deeds. And Yeah alchemy is in such a grey area that's kinda confusing, since there's a lot of settings in which it is a form of magic but there's also a lot in which it is basically rudimentary chemistry, and there's no elaboration of what it is here like they drop it in the story and then move along, like Xeroth is a fricking alchemist but we never get a elaboration of what that entails, of course that's not at all story relevant and I would imagine it's common knowledge enough so that the herbalist wouldn't need someone explaining it to them (an inhabitant of that world).
Also here's something extra to add to trust issues have you ever toyed with the idea that the third party is actually Feliar? Like who knows what nefarious secrets he keeps locked behind that door? I certainly don't! What is it that he hides?!