Great movie! First time I watched, when Chritoph Waltz pulled out the calabash, I thought, where was he carrying that thing? Waltz stole every scene he was in. (That's a good thing if you're an actor.) I'd say the pipes were integral to the "French Farmer Interrogation" scene by slowing it down. The audience gradually moved from wondering IF the French farmer would rat out his neighbors to wondering WHEN he would clearly decide to do so, and HOW he would do the evil deed. The pipes helped set the scene's pace and we watched a sturdy French Everyman struggle with swapping his own family's lives for those hiding in his crawl space. It was much more riveting to allow this to unfold gradually rather than quickly. And the calabash added a bit of black comedy to this black scene. I think in the rest of the movie Waltz is strictly a brusqe cigarette guy and Nazi prick.
Also, Christoph Waltz reprised basically the same character in Like Water for Elephants. No calabash, though.