The link I posted in the thread discussing warped rotors talks about how to break in you pads. It's pretty much the same as Fishexpo recommends.
One primary reason that many cars have rear drums: It has to do with the way they work. Disc brakes give you proportional braking, whereas drum brakes multiply the brake force. In other words, if you press twice as hard on drum brakes, you get 4 times the brake force.
This comes in handy for the parking brake, which is applied to the rear brake drum. The multiple effect gives you a good, strong parking brake that is less likely to give. Cars with rear disc parking brakes are prone to creep on hills once the brakes cool down. If you go to websites on manual tranny cars with rear disc brakes, you'll see that this is a problem. For a mainstream, high production car like a Corolla, this is a big issue.
Some luxury brands (Mercedes & BMW come to mind) actually have a rear disc and a mini rear drum brake which is exclusively for the parking brake. The added cost would not be feasible for a Corolla.
Rear brakes do significantly less than half of the braking on a car. That's why rear brake pads last so long. Old cars with front drum brakes tended to lock up and skid very easily when you slammed on the brakes. Since rear brakes take a huge amount of force to loock them up, drum rear brakes are fine for all except the most extreme stops. It's a design compromise, but you rarely are in a situation where it's an issue. It's a bigger issue if the front wheel lock up.