Check your barrel. If it says it's rated for .223 ammunition, firing 5.56 could cause damage. 5.56 is a higher-power load. If your barrel is rated for 5.56, then you're all set! Failing to find the barrel's rating:
Bushmaster's web site and catalog can answer your question.
While they are similar, the cartridges are not the same, with slight differences in the shoulder angle, length of neck. It is safe to fire .223 in a weapon chambered for 5.56, but 5.56 ammo in a weapon chambered for .223 may NOT be safe.
No.
No. You should never try to load or fire any ammo into a gun other than what it is designed to fire. A .44 caliber gun is designed to fire .44 caliber ammo.
9mm
The M4 is capable of automatic fire, the AR 15 is not
The AR-15 rifle has a fire rate of 800 rounds per minuteand a muzzle velocity of 3,200 feet per second.
Generally speaking, no, and, you should never try to fire any ammo from a gun other than what it is designed to fire. You may be able to get it to fire, but you could damage the gun or hurt yourself.
No
metal
Yes.
NO
Check the owner's manual.