If your rotors don't shake when braking then don't worry about it. If they do, call your local autoparts stores, some have a brake lathe and will do it for cheap.
To replace your pads you have to remove wheels, unbolt the lower caliper bolt then swing the caliper up and out of the way. Remove pads and lube any slide or friction points. Re-install pads. You should lubricate the pins your calipers slide on but if you can't then, just re-install caliper and wheel.
