I'd be inclined to think that you've either mistaken a ready position for something else, or else have fallen into a snipe hunt. The ready position is a tactical carry position - there are no steps to it, as it is not part of drill, and there's a few different ready positions, the most common being a ready carry for patrol, then you have your high and low ready positions for high alert situations.
Alert Carry is the weapon pointed downward, the downward carry is similar if not also known as the Low Ready. It is the modern form of carry today as people would rather risk an Accidental Discharge (AD) on their foot vs. their head or someone elses. I was thought it easy to remember as "alert to the dirt". Carry vs. Ready: Carry means just that, and Ready means just that as well, when a weapon is pointed at a target it is known as (sometimes High) Ready. The opposite of Alert Carry is the Tactical Carry. The Tactical carry is the older and lesser used today by the military as it points the muzzle to the sky diagonally across your body.
Metal - forged T70/74 aluminum, specifically. The only plastic components on the M16 are the buttstock, grip, and handguards.
Magazine
Magazine assembly
A M16 cost about $2000.00
M16 A4 rifle. That's why they use it now instead of the M16 A2 rifle.
M16
The M16 was invented @ 1960
Not usually. Your weapon depends on the job you have. For example, a rifleman will carry an assault rifle such as the M16, whereas a support gunner will carry some sort of LMG such as the M249 SAW or the new M27
They can carry it on either side of their body, using either arm. They can carry any firearm, it depends on the situation. Examples include M16-s or muskets in the US.
On the real steal and any realistic airsoft versions you simply need to unscrew the giant screws on the side of the bottom of the carry handle. If there are no screws then I think it can't be removed.