I finished "Everything Wrong With Nancy Drew: Secret of Shadow Ranch"!
According to multiple comments on the video, you CAN get a conversation about Tex's birthday on Day Three. I tried, but I couldn't get it. Also, the random pink food is cattle feed; there's a hotspot for it in Tex's area, by one of the saddles you're not supposed to look at.
And while looking at the bookshelves on Day Two, I found the hidden passageway! Pull on the book in the lower/left. I'm guessing this isn't triggered until you find Dave in the hidden passageway, but I guess it's worth checking to see if you can trigger it earlier.