We carry all our dishes and most of our non-refrigerated food in the cabinets below and to the right of the stove. We got tired of getting down on our knees to rummage through those cabinets, so I built and installed drawers in them. It wasn't hard, and it was by far the most valuable change we made to our TM.
The opening above the refrig is, indeed, intended for a radio. It is the standard-size opening (formally called "single-DIN size"
that accepts almost all car radios/tape players/CD players, etc. You can use a table knife to pop the cover off the opening (it is just held on with a couple clips), and you will find all the needed wiring lying on top of the refrig.
Welcome aboard!
Bill
[By the way, it looks like you posted your query twice. You should probably go the second one and click REMOVE. Thanks.]