Is a monk allowed to receive money? I have seen different answers to that question, so I assume it varies from school to school, is it right? 

I am not talking about donations to the Sangha as a whole, like a fund, but giving cash to a monk.
According to the Monk's Sila, they can not accept money, since money is related to sensual pleasures. Therefore when monks have to deal with money, it's better to take help of a lay follower. In Sri Lanka, in the past and even nowadays in some places, there's a lay follower called "abittiya" is residing in the temple or the monastery to intervene in actions like dealing with money in order to help monks. In some occasions the chief donater of the temple too engage in such activities to help monks. So it's better if someone can help monks in such actions because it's a great help and also a meritorious act since it help a monk to protect his Sila.