Why dont you just make a trigger that says if you select a unit and the unit is a type equal to some ward, then deselect every unit? That should work well enough.
Locust is actually the ability ALOC which makes the unit unselectable. There was a disscussion about this a year or so ago, concerning which effects the ability have got. The thread is prolly gone by now but u could try and search for it.
Yea, this will do...
U can also change the selection size to 0
But locust ability (U can find it at the locust's ability at the undead special section)
Yuo might changing what it can be selected as to nothing :S
In object editer, select the ward and go
combat - targeted as then deselect all the boxes? If i had the editor installed atm id take a look for ya but that may work?