Hi @drexocom, how are you? So about your questions:
1. Not necessarily, the power supply comes from the RPi connection but you can use a micro-usb power connector also. So you could use the MATRIX Voice without the Rpi. No, the $55 and $65 versions doesn't come with the RPi.
2. No, the ESP32 model it's designed to be a stand alone wifi/microphone communication. As said before the MATRIX power configuration comes from the RPi connection (or the micro-usb).
3. Yes, the cheaper versions doesn't come with the RPi so you will have to buy the power supply for it.
4. Humm, my opinion, i think the second option would be sufficiente for your use case, and you won't need to buy anymore itens. But if you want to go to the first option using a computer in a different room, i asked my colleagues about it and you could stream the audio to your computer with a cloud round trip, but we don't give that support.
You can look on our docs too and our github repository:
If you want anymore information just ask, have a nice day