Can't think of a solution to the first question you pose.
The CD50 had display features that were excluded from the later CD players - the Master Control Panel for the 5500 and 6500 plus the Beolink 7000 took on that role.
You should be able to connect it up to the Aux input and provided it has a 7 pin datalink then I do believe it should work on and off with the rest of the system.