visibility is just the opacity of your object....
to disable it create a condition which you can set inside of the properties section of the object itself; depending on whether or not you set it to negate the object will only be visible/active depending on if the assigned condition is true/false.
yes it's possible to do if queries within VS; albeit creating complicated if queries in vs itself is somewhat confusing due to how they end up looking in the action blocks... I find it much easier to create complicated if queries with Lua instead; but each to their own.
I'll create an example later, when I've woken up properly.