Tankers...
The following is based on my experience. I was in for 4 years. Spent 2 in Germany from 88-90 and the rest split between stateside and Saudi/Iraq in Desert Shield/Storm.
Tankers do basic training and advanced individual training (AIT) in one 15 week blast. So, coming out of training, they should have various physical skills, some weapons familiarization (qualify with .45/9mm and M16), map and radio skills, and some driving (though not much). I put general soldier skills (either trained or ingrained) at:
General Soldier Skills: Climb, Jump, Gamble, Bluff/Sense Motive, Intimidate, Knowledge (tactics), Knowledge (streetwise), Survival, Knowledge (popular culture), Hide, Listen, Spot, Search, Survival
Tankers break down like this:
Position - Where they 'sit' in the tank.
Rank - Typical rank for the position (though it's somewhat fluid)
Abilities - Important abilities for the position
Primary Skills - Skills that match their primary job.
Secondary Skills - Skills that match their other responsibilities
Primary Weapons - Weapons they're responsible for maintaining and qualifying with
Secondary Weapons - Weapons they may have qualified with in the past.
Tertiary Weapons - Weapons they have a familiarity with and may train on but don't have to qualify with.
Duties - Their typical responsibilities within the crew.
Loader - Typically new or a soldier that's short, strong and fast.
Rank: Pvt - Spc
Abilities: STR, DEX, WIS
Primary Skills: Spot, Listen, Repair,
Secondary Skills: <Radio Use>, Drive, Navigate, Treat Injury
Primary Weapons: M240 (manual, vehicle mounted), M16, .45 pistol or 9mm
Secondary weapons:
Tertiary Weapons: Tank Main gun, M240 (fire control, vehicle mounted), .50 caliber (manual/scope assisted, vehicle mounted)
Duties
When not loading the main gun on a tank, the loader's main responsibilities include: Guard duty, care and feeding of ammo for all the weapons, supplying the tank with food, water, and other consumables, and assisting in maintenance of the tank. The loader is the only crewmember responsible for qualifying with the M16. Though no one must qualify with the M240 on the loader's hatch, the loader does get some experience with it during gunnery.
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Driver - Typically a 2-4 year veteran. Driver's have to be less than 6'5" (I know because I'm 6'5" and just fit into the hatch).
Rank: PFC-Cpl
Abilities: STR, DEX, INT
Primary Skills: Drive, Repair, Spot, Listen
Secondary Skills: <Radio Use>, Navigate, Treat Injury, Hide
Primary Weapon: .45 or 9mm pistol
Secondary Weapons: M16, M240 (manual, vehicle mounted)
Tertiary Weapons: Tank Main gun, M240 (fire control, vehicle mounted), .50 caliber (manual/scope assisted, vehicle mounted)
Duties
The driver's main responsibility is to drive the tank. The driver is primarily responsible for maintenance of the entire tank, as well, though all crew members typically assist in this endeavour (big job). The driver also assists with guard duty, supplying the tank with ammo, food, water, and other consumables.
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Gunner - Typically a veteran > 4 years.
Rank - Cpl - Staff Sgt
Abilities - INT, DEX, WIS/CHR
Primary Skills - Spot, Navigate, <radio use>, Knowledge (tactics), Computer Use
Secondary Skills - Drive, Treat Injury, Repair, Hide, Move Silently, Listen
Primary Weapons: Tank Main Gun, M240 (fire control, vehicle mounted), .45 or 9mm pistol
Secondary Weapon: M16, M240 (manual, vehicle mounted), .50 caliber (manual/scope assisted, vehicle mounted)
Duties
The gunner's primary responsibility is to shoot the main gun and the coaxially mounted M240 machine gun. Additionally, the gunner is typically left in charge of the tank when the tank commander is away, and is generally responsible for discipline of the crew and maintenance of the tank. The gunner is also responsible for the maintenance of the fire control system (a fairly simplistic computer and its supporting components). In situations where the tank commander is an officer, the gunner is typically the ranking NCO on the tank and is ultimately responsible for the crew.
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Tank Commander - Typically a > 8 year veteran
Rank - Sgt - Sgt First Class or 2nd Lt - Colonel
Abilities - CHR, INT, WIS
Primary Skills: Knowledge (tactics), <Radio Use>, <Encryption>, Spot, Navigate, Diplomacy
Secondary Skills: Drive, Repair, Treat Injury, Hide, Move Silently, Listen
Primary Weapon: Tank Main Gun, .50 caliber (manual/scope assisted, vehicle mounted), M240 (fire control, vehicle mounted), .45 or 9mm pistol.
Secondary Weapons: M16, M240 (manual, vehicle mounted)
Duties
The tank commander is ultimately responsible for everything on the tank and everything her crew does. The tank commander role is to spot targets and lay the gunner on them, fire on targets with the main gun, coaxial mounted M240 machine gun, and the .50 caliber machine gun. He must also coordinate with/direct others in his platoon, company, battalion, and/or brigade via the radio (including calling in fire missions from air support and artillery), direct everyone in the tank over the intercom, navigate the tank through the terrain, and generally be a total bad@$$. Typically, green lieutenants are not total bad@$$'s, but follow the lead of their experienced NCO's to learn the skills needed to lead the tank and their platoon (at least the smart ones do).
Some random tanker trivia
Tank Platoon Make up:
1st Section
1 - Platoon Leader (1st or 2nd Lieutenant)
2 - Sergeant-Staff Sergeant
2nd Section
3 - Sergeant-Staff Sergeant
4 - Platoon Sergeant (Staff Sergeant or Sergeant First Class)
Tank Company Make up:
1st Platoon (4 tanks) White*
2nd Platoon (4 tanks) Blue
3rd Platoon (4 tanks) Red
6 - Company Commander's Tank (Captain, typically) Black
5 - Executive Officer's Tank (1st Lt, typically) Black
* This is the Platoon callsign on the radio. Thus, White One is the 1st Platoon Platoon leader's tank, Red Four is the 3rd Platoon Platoon Sergeant's tank, Black Six is the company commander's tank, etc.
Tank Battalions are somewhat fluid depending on the situation. They may have up to 4 tank companies or half tank half Bradley companies, or some combination. Typically, there's a Scout Platoon/Company made up of Bradleys and dismounted infantry, as well as a logistical company (Headquarters), with liasion with air support, artillery and other support services.
Training
The smallest 'operational' unit in a tank company is a single tank. The tank company is trained to operate at the individual tank, section (2 tanks), and platoon level at gunnery and the company/battalion/brigade/division/army level during field maneauvers.
EDIT: Also, the minimum crew for an M1A1/A2 is a TC, driver and loader....
Anyway. Hope this helps.
. In assigning Charismatic and Smart levels to officers and NCOs think about your concept for the officer. Is he a military genius? Better go for Smart and maybe one or two levels of Charismatic. Is he a leader you'd follow into Hell? Go for Charismatic with one ore two levels of Smart. 
