Wow! Lot of questions, maybe I can answer a few. Patrols were usually just sent out to get information about the enemy they faced or sometimes to "snatch" a prisoner. This type of patrol generally didn't go very far at all behind the enemy lines, if at all.
As for size of the patrol depends, but usually not that many men went. To many men moving forward is called an attack
Just having some fun with that last sentence.
As for freindly fire incidents you're right about the use of passwords, as for stumbling back to the wrong location, or late, or all the other things that could go wrong, I'm sure there were friendly fire incidents.
As for different approaches to patroling between countries I believe, (someone correct me if I'm wrong) that the Russians were much more agressive in sending out patrols, probably followed by the Germans then Americans. I once read somewhere that Americans only fought from "9 to 5" if they could. One other German soldier said something to the effect that the Russians would "keep you up all night."