Dont know if this has been posted before but when you give a unit a path you can check the lines of sight at every waypoint by clicking on the white dot and then press "T". I use this to check if an endpoint gives me a hull down position.
The same way you can assign every possible commands at waypoints e.g. cover arcs.
I always confirm my move orders by right clicking when Iam done. Then I click the little white dots and pyramids and give ordes at every waypoint. That always works for me.
I just tried it and it works. Its important to remember that the LOS always comes from your vehicle not from the waypoint itself. So this may be a lttle bit confusing.
Yah like Seydlitz said, we can do wonderful things with waypoints, i've still got to test it all out but I just did a brief test in the 'Waypoints' thread