"Which male celebrity do you like?"
Usually we only call someone 明星 if he/she is renowned for being an actor/actress or singer, or having engaged in other types of performances or sports.
In Spanish too, so I felt the same. There are lots of words like this in Chinese. Love Chinese :).
I think that 哪位 is even better than 哪个 because of the standard Chinese using 位 to identify the differences between human and others. So 你喜欢哪位男明星should be the right translation.
No it is not accurate to say so. Human can also be counted using 个. 位 is honorific.
You asking a friend : 哪个
You asking an actress as an entertainment reporter before the camera : 哪位
什么 means What, so it's just like in English we won't say "What male celebrity..."
We can use 什么 for the type of person (like profession, nationality, etc.) in a casual way, e.g. 什么人给我们派信？邮差。