Anywhere from $75 to $375, depending on make, model, and condition. Your question is too broad to answer accurately- can you narrow things down a bit?
The cost of a 357 magnum revolver depends on many factors, it's condition, whether it's new or used, and what model it is. You can find them from 350 dollars upwards.
HOW OLD IS THE INTERARMS ROSSI MODEL 713 AND I NEED A DIAGRAM AND PARTS LIST
That depends on make and model. A typical "snub nosed" compact .357 Magnum revolver would hold five rounds, whereas a full sized revolver will usually hold six. The Desert Eagle .357 Magnum has a standard magazine capacity of nine rounds.
"Magnum" refers to the cartridge, not the firearm. The Desert Eagle fires Magnum cartridges. What you're probably asking is the difference between a revolver chambered for Magnum cartridges, and a Desert Eagle semi automatic pistol. Of the two, the revolver would typically be much more practical.
50-75 USD
100-1000 or so depending on EXACTLY what you have.
A .44 Magnum revolver typically weighs around 2-4 pounds, depending on the manufacturer and specific model. The weight can vary slightly based on features like barrel length, grips, and material used in construction.
Less than 100 to over 1000 depending on specifics.
100-400 or so
Could be anywhere from $100 to over $1,000, depending on WHICH revolver, and it's condition.
as much as somebody will pay!
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.