enough to fill the master cylinder
1 quart
A brake repair for a 2004 Ford Mustang costs about $1500.
http://auto.howstuffworks.com/1965-1966-ford-mustang-specifications.htm
about 4 quarts
is it auto or manuel?
No.
In the 1993 manual transmission Mustang the capacitie is 5.6 pts.
yes because brake fluid wont wear out as much No, brake fluid will destroy the seals in the power steering system.
A few reasons. Fluid has a much higher density, and makes it easier to apply more force to the brakes. Fluid is much easier to contain and refill. No special equipment is necessary to fill a brake fluid reservoir.
320 / 325 brake horsepower
nothing
brake fluid absorbs moisture thus brings the boiling point of your brake fluid down to a much lower temperature. if your brake fluid reaches this temperature you can loose your brakes temporally. also the moisture in the fluid will cause highly unwanted corrosion of internal parts of your brake system.