I would opt for a beomaster 5500/6500/7000. These are more than powerful enough to push all of those speakers. (I used BM5500, now a BM 7000)
These are really superb units with plenty of power and easily available 2nd hand and worth the small investment. They have the optional advantage that it's easier to connect other (both B&O and non B&O) items to, like cd players etc.
I tried a BC9500 which I found limited to pull a full MCL system.
Their should be a small-ish white box in each room, though I know some people have them actually built into the wall ....
The dial could just be a manual dimmer for the sound mounted between the mcl2 box and the speakers (I used to have one like that in my bedroom) Makes the room controllable manually and I guess avoiding investment in an extra remote for that room.
The black box (MCL2p amps should not be necessary imo). Fun is that you can use a BL1000 remote to control the system in every room.