Below are some considerations:

If the turntable has a built-in preamp you have some wiring options. If the turntable does not have a built-in preamp, do not extend the wiring between turntable and preamp.

Turntable above the TV would likely be inconvenient to operate.

I don’t recommend placing the turntable on the same shelf with SONOS FIVE because there will be some unfortunate coupling between bass from the speaker and the turntable.

If the FIVE’s are used as surrounds, their Line-In will be disabled.

Unless you will be using 3rd party passive speakers in a stereo configuration, AMP would be excessive, PORT would be a better plan because PORT and the turntable could be located at any convenient location within wireless range.

Yes, you could use an analog audio to optical converter and swap the optical input to BEAM as needed. Operationally, swapping could become annoying after a while. An optical switch could help. Rule of thumb is that optical cable length should be limited to five meters, but high quality optical cables are probably viable to about 10 meters. I doubt that one could use an optical switch and 10 meter optical cables, but I have never tried this.

Awesome. Great info. I was only looking at the Five as to add another speaker to the room/house, but it sounds like the Port is the right solution for the space. I guess I could set the Five horizontally on shelf 2 and run the wire from the turntable behind the sectional (~15 ft), but I don’t know if the room would even configure that with the playbase and two surrounds. It sounds like it would just treat the Five as another surround? 

Surrounds must be used in identical pairs. A single speaker cannot be used as a surround.