No you dont need the spindles unless you want to upgrade the brakes to a larger diameter rotor or go dual piston calipers.
All you need is mustang 94+ front rotors and ABS front mustang hubs. You can reuse your factory calipers.
For the rear you can redrill your stock hubs and redrill a set of stock rotors. And be done, but mustang wheels will need hubcentric rings to be hubcentric.
The alternative is getting cobra Hubs and getting cobra rear rotors. Then get Adapter brackets to relocate the stock calipers. .