To control this you need one of the following:
The most basic remote would be a Beolink 1000. This is a one way remote and will allow you to select sources, tune the radio and control the sound.
The next cheapest would probably be a MCP-5500 or 6500. This will allow you to program the unit's timer as well as all the source and sound functions. It is a two way remote and displays what the system is doing.
The last remotes are the Beolink 5000 and 7000. The last is the most complex and is very sophisticated. It would allow you to control every function on any source attached to the Beomaster 7000. It is however complicated, expensive and getting old so not so reliable.
I would suggest that an MCP-5500 and a Beolink 1000 would be good investments as the Beolink 1000 is a very good everyday remote and the MCP will allow you to access the programming functions. A Beo4 would act in much the same way as a Beolink 1000.
As far as manuals are concerned, you can either join as a gold or silver member here in which case you will find all the manuals are downloadable or you can join the official B&O site where they have a manual for the Beosystem 6500 available which is pretty much the same which the same operating system.
To get something now, put the system together, put a tape in the Beocord and start it and the Beomaster will turn to the Tape source - you do not have any control over the volume except with a remote though. You can actually cycle through some other sources, namely the radio stations by attaching an aerial and pressing the side of the Beomaster labelled STEP. You can also mute it by pressing the other side and can switch it off by a prolonged press on the same side.