u do not assign any other function (digital in or out) to those pins.(SPECUALTION AHEAD!)as for RTS and CTS (ready-to-send/clear-to send) on your bluetooth module you can just connect them to each other i guess. those lines are used for flow control, i.e. to signalize that a device is ready to send or receive data. if you experience problems you might bypass/grab those line from somewhere on the bo