Before setting the device in the master mode, make sure you have another device which is in slave mode. I have HC-06 which is always in the slave mode.
Starting with the simplest one i.e using the POLL method. The data is Received in blocking mode i.e the CPU will block every other operation until the data transfer is complete. This method is good to use if you are only using UART and nothing else otherwise all other operations will be affected.
The data is transmitted in blocking mode i.e the CPU will block every other operation until the data transfer is complete.
Stepper motors generally comes along with an IC ULN2003. This IC is used to drive motor because microcontroller pins are unable to provide sufficient current to drive these motors.