The couple is required to fulfill all of the obligations imposed upon the wedding of two Catholics. (ie: Practicing Catholics)
In addtion, from the Roman Catholic Point of View, I would discourage a Mass (Eucharist celebration) but celebrate a Nuptual ceremony. The couple must request a dispensation for mixed marriage and the Catholic Party must sign the document stating that all children of the union will be baptized and educated in the Roman Catholic Faith.
Should, for a substantial reason, the couple wish to marry in the Protestand Church the may apply for the proper dispensation.