@Melonlity -- you've touched on one of the primary reasons to get an expert to replace those pads instead of doing the repair yourself. Of course, there are amateur mechanics who know what they are doing when it comes to replacing those things, so this advice doesn't apply to them.
Here's the thing. If you don't get the pads put on just right, you could warp your rotors. If you don't get the hydraulics working just right, you could warp your rotors or wind up without brakes.
By the way, if you do wind up with a warped rotor, consider spending a few extra bucks to get a heftier, performance grade one. It will costs you a little extra, but it is far less likely to warp in the future and can actually improve your braking. Those are both very good things.