If I went with this solution, I assume a phone call would come over the speakers; however, wouldn't I need to unplug for the caller to hear my voice?
The call will come over the speakers as long as you are listening to the phone audio. If you are listening to the radio or some other source, you will need to switch to the phone source to listen to calls over the audio system.
You will not need to unplug the phone for the caller to hear because the phone only switches the audio output to the headphone plug while connected, the audio input stays live on the phone's mic.