1. glaze usually occurs when the pads become contaminated, when the sustance holding the pad material together is dissolved by a solvent or some such, try taking a metal file (a CLEAN ONE) to it lightly untill the sheen has gone, but usually if the pads are glazing up its game over.
2. no need to swap rotors, just swap out pads.
3. when its bent. its extreamly rare for a rotor to live long enough for it to wear out, remember, when you put the brakes on, its not brake pad against metal, its brake pad against brake pad material deposited on the rotor (hense the bed in period) dont worry if your rotors are glazed and mirror finished, this is good.
4. yes, just losen the nut and pull some more cable through. if you had to replace the cable every time they stretched, youd have to get new cables every 2 weeks. cable stretch only occurs on new cables, or really really really old ones that are about to snap. A new cable always needs to be stretched and bedded in to an extent.