Well, as I just did this about 5 minutes ago, I can tell you the Feyruh potion is in the laboratory with the Ranaar who is allergic to wine, hates poetry and tail-tickling. To enter the door, you have to talk to the Ranaar outside. It's really close to where you got the summoning quest.
About the Kohar root: The guy in the (what appears to be) pharmacy tells you an imp has it. (Hint hint)
Tovi 