A 44 magnum is just the new and improved version of the 44 special which the special is a 44 caliber. Magnum just means bigger so the 44 magnum is pretty much in between 44 and 45 cal.
However, if you mean size, .45 is slightly larger in diamater than .44.
I'm not aware of a .45 Magnum. There is a .44 Magnum. The 44 magnum is typically a revolver round, very high power. The 45 ACP is typically used in semi-automatic pistols. The 45 ACP is not as powerful compared to the 44 magnum (mostly due to the amount of propellant in the 44 magnum compared to the 45 acp).
Depends on which 45 and which 44 chambering you are talking about the load
The longer case of the .44 Magnum holds more powder, and, even though the .44 is smaller in diameter, it tends to pack a heavier projectile, ranging from 240 to 350 grains, vs. the typical 165 to 235 grain projectiles used by the .45 ACP.
No. If it will even fit (the rim of a 44 magnum cartridge is much larger than a 45 Colt) it would be very dangerous to do. 45 Colt firearms were not designed for the forces of a 44 Magnum cartridge.
A 44 magnum is more powerful than a 45calibur
Impossible to answer without knowing which 45 you are referring to. 45 ACP, 45 Colt, 45 Magnum, etc..
It depends on what you mean by bigger, but the answer to the question you're probably asking is yes. A .45 caliber bullet is .45 of an inch in diameter. A .44 caliber is .44 of an inch, so it's slightly smaller in diameter. However, .44 caliber bullets are many times longer and heavier. A common weight for .45s is 200 or 220 grain, and for .44s it's usually 240 grains.
It depends on the load
No.
No. There was a 45
It's 12.7mm. Calibre is 1/100th of an inch. So, a "50 Calibre" gun, which is what a Desert Eagle is and on paper would read ".50cal", after the conversion to mm, which is 25.4mm to 1", would be 12.7mm.
In most circumstances, no. The bullet is too large to chamber in the handgun.