After setting up a Serial Port Profile for a Bluetooth device, should I be able to use the .NET Serial Port class to read from and write to that device, or is it more complex than that? Would someone kindly explain how this works?
That's correct. Once your device is paired and the profile is working and the drivers are loaded, you can access it just like any other serial port on your computer.
You can't however, get Bluetooth management info that way, such as signal strength and pairing status. For that, you need to use the API for whatever Bluetooth stack is in use.