There IS a crosshair, but you can disable it, as well as the HUD. I think you do this by making it completely transparent.
However, there are map objectives that you may want to keep on. There's a minimap for team mates, but you probably don't want that either.
And injuring or killing team mates deducts ROE, and enough ROE deducted can result in decreased honor (you start with 10 honor)
You also bleed when shot. I think they're changing the medic system. but in AA2, soldiers have a field dressing that decreases the bleeding rate and makes the medic's job faster.