Headscratchers / The Nature of Predators

• If everyone has a universal translator that can automatically interpret both speech and writing, why do they need to invent an auxiliary language like Common? Sure the characters comment that it's considered pretentious and only used by diplomats, but still...
• It's implied the Farsul may have genetically pigeonholed certain species into specific roles. If they're the ones who decided the Zurulians would be the doctors of the galaxy, why on earth did they pick a species whose hands are also their feet? That has to be a hygiene nightmare.
• The Yotul are only "uplifted" 20 years prior to the beginning of the story. Life before First Contact is still well within their living memory, and they keep small carnivores as pets prior to the exterminators torching most of the population, meaning the Yotul never subscribed to the Predators Are Mean notion prior to meeting the Feds. The marsupials are also the victims of quite a bit of Fantastic Racism from other Federation races. With all that in mind, you'd think the cracks in the Federation's facade would start showing with them rather than the humans.