The speakers come with a microphone and you should buy a microphone stand for a few quid. The app and online video guides you through the room compensation process. It applies correction across the audio band but is also tweakable if you fancy a little extra bass or little less treble etc…
Secondly, the radiation pattern or beam can be rotated if you sit in different parts of the sofa or the room. You can do calibration for the different listening positions. The beam width control can be set to wide or omni if you have a party so the sound is less corrected rather like a lighthouse being turned into a camping light radiating in 360 degrees.
The DSP also checks impulse to ensure sounds start and decay as accurately as possible.
I have never moved them as the room calibration negates the need to move and experiment. The ideal placement is described in the white paper.
Yes, you can add a Naim front end or front end of any kind. I use Toslink and Coax digital in. It has analogue RCA and XLR balanced. I have a record player into them. The digital inputs are all upsampled to 24/192 before being sent to DSP that applies filters to all 14 speakers per channel.
Finally, the speakers compensate for each other in a room as the contribution of both can setup reinforcements, nodes. This is a step up from previous generation of Beolabs that only corrected for one speaker alone and the Room.