I've had two front calipers seize up on me a couple of years apart. Neither made that much noise, but it's consistent with what you describe. In my cases, I had warped rotors and I would feel the drag as the warped part of the rotor hit the pads. After 50 ft or so, the warp in the rotor pushed the pads out of the way. Also, my gas mileage gradually dropped by a 1 - 2 mpg and recovered immediately after replacing the caliper (and rotor & pads, of course).