Well from what unit's eyes are you doing this movie from? which branch of service? I'm assuming since you want an open desert kind of look you'd being going with 3rd ID or supporting elements, who went up through the open desert and on into Baghdad from the west.
But like I said you should look at exploring other options as far what time line you want to shoot this in....... Your not gonna get the right look and feel.
Really what you should do is get some books on the Invasion there's at least 100 different books out there! I'd recomend "Ambush Alley", "Generation Kill", or the book about my unit "The March Up" all those books are more of the Marine Corps experince and each is about 1st Mar Div's battle to Baghdad, but each is written from a different view point. Also there are alot more books about the 82nd, 3rd ID, and the 101st written as well, if what your looking for is the Soldier's perspective.
Remember your script is gonna need to be written the way warriors speak, and trust me it isn't "ghost recon 2" or "saving pvt ryan" you need to know the accronyms, the jargon, like Marine's aren't called Soldiers, and nobody calls a Sgt, "Sarg"........
But as I said unless you can get MOPP gear, everyone armed with an M16A2 (very very very few M4's during the push up) with a few SAW's, 50 cal's, MK-19's, a few hummvee's and a couple of 5 tons at the minimum, anyone who knows is gonna see right through your movie.
Thats why I really think you should make up a fictional story in the not so distant future.
Or maybe contact a few of our other National Guard Soldiers that post here about A-stan. They can better describe the sitiuation going on there, maybe give you some idea's. And of course pick up some books and learn your medium.
Trying to make a real movie based off something like this with zero knowledge and resouces is a bad idea.