It's like this:
Replace your pads when they're worn out. Mileage doesn't matter, pad type doesn't matter for this, there's no rules, it all depends on driving style and braking habits. You can eat a set of pads and rotors in a weekend at an open track event or have them last 200,000kms on a highway vehicle or anywhere between. Just replace them when they wear out. Check pad wear by looking through the inspection hole in the rotor whenever the wheels are off, the more often the better. Make sure to check each pad too, that means inside and out, usually one will wear faster than the other. If they squeel or grind look at them ASAP and get them changed. A really loud squeeling/howling fingers on chalkboard type sound is the wear indicator on the brakes hitting the rotor telling you to change the pads now. But don't wait for it, I've seen pads worn to the rivets that never hit the wear indicator.
Warped rotors are fairly common, they'll show up as a shake or shimmy in the steering wheel when you are braking. It's not really a major problem... The car will still stop fine, it'll just shake the wheel when you do it. To fix this you need to get them turned down.
Any shop with a brake lathe, or even Lordco and some other parts stores will turn your rotors down without doing the brake job for you.... as long as the rotors don't need to be turned below minumum thickness. No one will turn rotors below min. for liability reasons and you shouldn't run them anyways.
