Not quite correct in your explanation of biliary obstruction. If biliary outflow is obstructed, more soluble conjugated bilirubin is excreted into the urine (because it cannot go into the GI tract due to biliary obstruction), causing dark urine. The obstruction prevents excretion of conjugated bilirubin into the GI tract, so less urobilinogen (and later stercobilin) is formed and you get pale stool.

Edit: also, gallbladder obstruction would give you cholecystitis but would not give you symptoms of obstructive jaundice like dark urine or acholic stool