I'll note that I let myself get bogged down in the Lighthouse, too, as I figured it was important, but then I followed a blind trail for the conversation.
But then I astravel'd away and back again, and Cheree's opening dialogue pushed me where I needed to go. This helped somewhere else, too, (where isn't important--just the general mechanic to refocus myself) though for all the other clues, I didn't need it.