Ah yes... I do seem to recall that the FR plug suite that came on disc with my interface is 32 bit (I think). I just checked and it looks like there has been an update earlier this year to version 1.6 and it looks like it does indeed have 32 and 64 bit versions included.
 
As far as TH2 having an icon in the windows task bar when running as a plugin (as opposed to standalone which would certainly put an icon in the task bar)... I have never noticed that but will check it out. What you may be seeing is simply the application launch icon. When you installed TH2 I think it gives you the option to put pin an icon in the task bar (just like many programs). So perhaps you just never noticed it there when you've have Sonar closed or somehow the standalone version is being launched somehow instead of the plugin version inside Sonar. However the latter requires you own the full version of TH2 I think (which I own).
 
Anyway all that doesn't really help with the original problem aside from maybe getting the FR plugs to respond to the X-Ray feature.
 
Like I said earlier I think you may be stuck figuring out a decent workflow to show/hide things in an efficient manner. Try out some of the stuff I suggested. It becomes second nature after a while.
 
Also you can find a list of keybindings in the manual and I also recommend taking a look at the "Tools" section of the manual which has some more detailed bindings. There are also other bindings scattered throughout the manual that are not on the list unfortunately. They may have corrected this in the X3 manual though as I've heard they updated it and did some work consolidating/cleaning it up to make it more accurate/concise.
 
Cheers.