Can you program each Transmitter to play a different tune? I'd like to know which door to go to when someone rings.

Starpoint/Crosspoint/Skypoint Doorbell: Yes, you can program each Transmitter to play a different tune.

PushPoint/Acepoint Doorbell: No, unfortunately each Transmitter cannot be programmed to play a different tune.

I have a STARPOINT Base kit and 1 Model LR. Can I set up the doorbell unit to different frequencies?

Yes the STARPOINT Models can be set to different frequencies.

Is there a instructional video showing how to setup or add on additional Receivers, Transmitters, or Sensors?

Yes, we have an instructional video posted here:

Does the Transmitter have a tendency to allow signals from other wireless devices to ring the doorbell?

No, this is a learning code doorbell and so it has randomly generated signals that has a rare chance to conflict with other wireless devices.

Do you have to purchase the starter kit, or can I just purchase the items I need and have them work together?

You don't have to purchase a starter kit. As long as you purchase parts from the STARPOINT models, you can just purchase the items you need and have them work together.

If I unplug the Receiver and re-plug it in a different location, would it keep the stored information, such as which trigger would ring which chime?

Yes, it will retain the configured settings.