That's a nice idea.
For the first, being detected only in a radius :
Using a script only activable by members who infiltrate witch contain the condition to being setcaptive false in a certain distance of any hostile soldiers.
Than, if in a highest distance, they switch to setcaptive true.
For the second :
The same idea, but when the members are close to the different objects.
Maybe using the Id's, or another command that can regroup all natural objects.
For that, I know that in A.C.E II, there is a GameLogic that enable AI Grass View Block.
Not really tested it yet, but I think I'll do it today.
I'm not a professionnal in scripting, I just do some things and I learn about it every days, but maybe I can help you with this ideas.