(Note: This is NOT an official United States Government website)
The Army was formed on June 14th, 1775.
It means "Government Issue" and it has a lot of uses depending upon the context. If you refer to somebody as a "G.I." it means they're a member of the armed forces; usually Army. If you refer to something being G.I. (ex: "Three pairs of G.I. green socks") that means it is official, government issue, equipment.
It can also be used as a verb meaning to get things in order. ex: "I want you guys to G.I. the barracks." which means to clean and make inspection ready.
Start here: http://www.goarmy.com/ or visit your local Army Recruitment office.
E1 - Private
E2 - Private E-2
E3 - Private First Class (PFC)
E4 - Corporal/Specialist (SPC)
E5 - Sergeant
E6 - Staff Sergeant
E7 - Sergeant First Class
E8 - Master Sergeant/First Sergeant
E9 - Sergeant Major
O1 - Second Lieutenant
O2 - First Lieutenant
O3 - Captain
O4 - Major
O5 - Lieutenant Colonel
O6 - Colonel
O7 - Brigadier General
O8 - Major General
O9 - Lieutenant General
O10 - General
General of the Army (doesn't have an "O" designation; is only used in wartime)
2.1.1 George Washington
Commanding general of the Continental Army he led the revolution against England that led to the independence of the United States. Subsequently became the first President of the United States.
2.1.2 General Ulysses S. Grant
2.1.3 General John J. Pershing
2.1.4 General George S. Patton
2.1.5 Audie Murphy
2.1.5 General Dwight D. Eisenhower
Supreme Commander of Allied Forces in Europe he oversaw the D-Day invasion of Normandy during WWII. Later became President of the United States.
2.1.6 General Douglas MacArthur
2.1.7 General Norman Schwarzkopf
The M2/M3 Bradley is an armored, tracked, vehicle with a primary mission of transporting troops in a secure, all-terrain, vehicle and supporting them in combat. You can think of it as something of a light tank, although that is not really it's official designation.
The M2 is the transport variant and it can carry up to 6 fully equipped troops, in addition to its 3-man crew. The M3 is more for scouting and reconnaissance and it carries 2 scouts in addition to the 3-man crew.
The Bradley is capable of just shy of 40mph on the roads and all of them are amphibious.
Here's are a couple of good sites about the Bradley:
Speaking a bit generally strategy is what you want to do (in the grand scheme) and tactics are how you do it. Attacking on the enemy's left flank and seizing a city that is key to their supply lines is strategy.
Having a tank advance to the corner and lay down suppressing fire while two squads of troops run across the street and take up advantageous positions behind a rock wall is tactics.
Indirect fire is, obviously enough, fire that is indirect. If you take a rifle and shoot something that is direct fire. You aim at it, your bullet travels in a straight line and hits the target (hopefully), directly. Indirect fire is mortars and artillery. The projectile is fired up into the air at a particular trajectory calculated to bring that projectile down, somewhere downrange, onto the target you want to hit.