No idea, I don't know where the AV plugs are located on the BC6, neither if the decoder will fit inside the plastic plate behind the TV. You should call MAD (it's the B&O repair center for all parisians B&0 dealers, excepted one) they will tell you.
Absolutely, the device manages everything:
channel zapping, record on USB key or external HD (as well as watching JPEG put on it), EPG, channels level reception and quality signal, picture settings, sound settings...
In fact you have the same capabilities than with the Televes remote itself, a mapping has been done to control the device through the Beo4 (or link1000, but easier on Beo4 because you sometimes need the EXIT button which is not available on LK1000).