As far as performance rotors... you won't notice much of a difference unless you are doing some heavy braking. The main goal is to dissipate as much heat as possible and slotting or drilling the rotor allows for air to vent out. If you are using the rotor beyond its capability, you will encounter brake fade, where the pedal will sink down. The rotor/pad/caliper will get so hot that the brake fluid will boil, causing the pedal to sink down as the fluid expands (which it shouldn't). If you don't encounter brake fade, you aren't using the brake rotor past its true capability.
As far as the "big brake" rotor kits. They replace the rotors with larger diameter rotors. They also replace the pads with larger pads and more powerful calipers. Big brake kits are outrageously expensive and only really only necessary if you are doing some serious racing.