As for making it stay put until you need it, take away the gas. In the plane's init field put "this setfuel 0" without the quotes. When the plane is called, probably with a trigger, put in the on activation field "plane setfuel 1" where plane is the name of your plane. Again, no quotes.
As for following waypoints fewer is generally better. I haven't done squat with laser designators and planes so I'm no authority on that sort of thing.
Good luck!