First Sergeant (E8).
The signature block for a company first sergeant typically includes their rank (1st Sergeant), followed by their full name, then "Company First Sergeant," and finally the company name and unit designation. For example: 1SG John Doe Company First Sergeant Company A, 1st Battalion, 123rd Infantry
E-8 for the actual rank. First Sergeant is also the senior NCO position within a company or troop, and sometimes might be filled by a promotable Sergeant First Class (E7), who will still be referred to as First Sergeant by those in the company.
Well...every other rank that isn't First Sergeant, I'm guessing...
YES
The life blood of a US Army company is the squad leader, regardless of rank. The typical rank for a squad leader is Staff Sergeant (E-6). The squad leader is responsible for the training and care of all soldiers in the squad. While the platoon sergeant, first sergeant, platoon leader, and company commander all play important roles, the person who is responsible to ensure the work gets done is the squad leader.
There is no such rank as "First Class Sergeant". You have either Sergeant First Class, which is E7, or First Sergeant, which, along with Master Sergeant, is E8.
Gunnery Sergeant is pay grade E7, and the equivalent Army rank is Sergeant First Class.
The lozenge is simply a device to differentiate a First Sergeant from a Master Sergeant, Sergeant Major, etc.
Master Sergeant in the Army is pay grade E8. First Sergeant is the other Army E8 rank.
Sergeant First Class is pay grade E7. In the Army, the next pay grade - E8 - has two ranks within it - Master Sergeant, and First Sergeant. The difference being that a First Sergeant is a company's senior NCO, whereas Master Sergeant tends to denote NCOs holding staff positions.
In the United States Army, the rank of First Sergeant (abbreviated as 1SG) is above Sergeant First Class, below the ranks of Sergeants Major and shares the paygrade of E-8 with Master Sergeant. The rank of First Sergeant carries more responsibility than the rank of Master Sergeant, and the rank may be either given to the soldier upon promotion to the paygrade of E-8 or they may be "laterally promoted" (promoted in rank but not paygrade) from Master Sergeant at a later date. They are also known unofficially as Top Sergeant or just Top, due to the fact that First Sergeants are the most senior non-commissioned officers in an Army company. Right - that is Current, but what was the difference during World War II, when Master Sergeant was technically higher than First Sergeant (Although both E-7)? - Master Sergeants were higher in responsibility than FSgt's. Master Sergeants were commonly Battalion level NCO's during WWII, also more experienced members of the Armored and Air Corps. First Sergeant was the most senior NCO positions in a Company.
I assume you are talking about E-8 and E-9 ranks. At E-8 you become either a First Sergeant or a Master Sergeant. If you take the First Sergeant route the next rank becomes Sergeant Major. If you take the Master Sergeant route the next rank becomes Master Gunnery Sergeant.