This a collection of facts, opinions, and thoughts, all piled up here.
I recently looked at a Youtube video showing some helmets from Halo 4, including the Warrior helmet (the standard helmet seem in most images), the Scout helmet, the Recon helmet (which now looks a little too close in appearance to the Scout), etc. The new Hazop helmet, unfortunately looks dreadful. The Orbital helmet looks like a mix between the EVA helmet, the Pilot helmet, and the Elite General armor from Reach.
Most who have read Halo: Glasslands (and understood it), have probably come up with the assumption that the Sangheili encountered and fought by the Chief and Cortana are the Servants of Abiding Truth, who may have declared war on the UNSC after ONI secretly armed them with Covenant weapons. This may not be true, because Avu Med 'Telcam, the leader of the Servants, promised that they would stay as far away from humanity as possible. It might also be that 'Telcam and the SoAT declared war on Thel 'Vadam (The Arbiter)'s faction of Elites, who signed a peace treaty with humanity.