R9 slim with pixhawk connection help

Hello i am planning to buy a r9 slim receiver for my r9m module for my tranis qx7 but i have multiple questions as i am new to drones and pixhawk:

1.how to connect it physically to the pixhawk
2. What is the telemetry receiver function on the r9 slim
3. What software changes do i need to do to my tranis and pixhawk

4. What is a uart port

Thank you best regards