It seems like modifying the Space names and numbers to match the room names and numers would be easier in a Schedule view since you could have a side by side comparison (see attached). Not saying your way is "wrong" but a schedule would allow you to quickly compare the two without panning around in a plan view. Just my $0.02.
As far as not plotting those parameters, all I can think of is creating two famly types within the Space tag family. One that just shows Room (or Space) name and number (Space Tag 1) and one that shows your modified parameters (Space Tag 2). When you are ready to plot, select a Space tag, select all instances, and change them all to (Space Tag 1) or whatever you name it.
Or Autodesk can add a "no plot" parameter in MEP 2010