For the first question, the option that is NOT a function of money is: Currency exchange. Currency exchange is a service that facilitates the conversion of one currency into another but is not a primary function of money itself.
For the second question, the primary reason money is often preferred over bartering in transactions is: It allows for the exchange of goods without needing a mutual desire. Money serves as a common medium that can be used to separate the act of buying from the act of selling, thus eliminating the need for a direct barter of goods.