My wife, native Polish speaker, said the same thing when she heard it. Jeż, pronounced the same, means hedgehog. So, she said when she was young and someone said "Co jesz?" ("What are you eating", which also sounds like "What hedgehog?"), they would answer "Co niedżwiedź?" ("What bear?") as joke.
No. Generally 'jaki' and its forms is like an 'adjectival what'. This is one of the hardest things to explain, but recently br0d4 finally thought of some explanation that makes sense in most cases.
So, if in English you just have a 'what' on its own, without any noun phrase, you are asking about the noun phrase. So you have "What is this?", "What do you want?" "What did you receive?" etc. - and you use "co" or its other form (as needed by cases, for example 'What do you want' is "Czego chcesz" as it needs Genitive).
If you have some noun phrase in the English phrase, you are asking about this noun phrase's 'properties'. And this is 'jaki' and its grammatical forms. So: "What colour do you like?", "What is your question?", "What people are they?" etc. use forms of "jaki".