Would it be appropriate to email a professor about the culture of an undergraduate college before applying?
Most colleges have this information available on their website. If there is any specific question you have that is not covered on their website, of course it is appropriate to email someone in the department and ask. But if what you want to ask, such as the admission requirements, is already posted somewhere, then by asking this you will come across as someone who does not bother to search on their own before asking them.