You will be able to get the haunted helmet, but first you have to buy all other helmets and parts for them, then you will be able to buy it for 1 credit as a variant of the pilot helmet. Here's a picture:
images4.wikia.nocookie.net/__cb20100908101712/halo/images/thumb/e/e1/Haunted_helmet.jpg/160px-Haunted_helmet.jpg
yes, you get JFO armor, and you get mark IV armor, and also a gold visor but that is the max rank.
You have to be an warrant officer in halo reach to unlock the helmet you also have to go to halowaypoint and unlock the armor.
There is two ways to get it #1 unlock all of the armor #2 is to become the highest rank in halo reach
The highest rank in Halo: Reach is Inheritor.
you buy it and you can unlock some by halo waypoint (free download)
inheritor
major with 140,000 points
Reach Lt. Colonel first, then check the price.
inheritor
Inheritor.
For now, no. Although, in the near future a new kind of armor might be introduced, much like Recon armor was in Halo 3.
Inheritor, the last rank in the game. The last helmet, the Haunted Helmet, is the Pilot Helmet with a skull on it. To unlock it, you must reach the rank Inheritor, and own every BASE helmet in the game.