Cosmetic plug for 3/4" hole in drywall?
A partial solution is to install cat5 jacks connected to each other instead of a straight through cable.



As for the power cable, that is a strange one.  Wouldn't it be better to have the wall wart and cable inside the room?  Trying to do a jack or cable running through a tight conduit is a recipe for built-in obsolescence and/or compatibility.