I watched Restrepo just a few days ago. You're right, a lot of those soldiers looked like they were young, but I'm surprised how young the senior officers look these days.
The captain was talking about the hescos before there was any reference to them, and since he was talkin about digging-in and they were filling those things up with dirt and rocks (and some dirt-filled sandbags), I figgered that was what he was talking about.
There isn't much of anything to use for shields in those mountains, so the hescos are a really good idea that is probably making some DOD contractor a lot of money. Taking the mountains apart with picks and shovels appears to be treacherous work with guns fired at them on a regular basis. So all of the shelter that's available comes from rocks and plywood with additional some framing lumber.
The landing zone in the valley seemed odd. The Restrepo soldiers were in a good position to defend it, but it looked odd.
The worst part was that the interviewed soldier commented that the gubmint doesn't have medical personnel qualified/experienced to treat the needs of the men that survive that kind of duty.