If all you're going to be doing are driving around the street and long trips, ie average road user, OEM rotors and pads are quite sufficient.
If you're more of a spirited driver, then a change of rotors will be good. I would say slotted rotors are good, but most importantly you'd want ones that could withstand the heat/cool cycles so as not to warp as easily.
In terms of good brake pads for both track and street, I've been recommended Ferodo TS2000s. I hear Bendix Ultimates are quite dusty (well.. so are the TS2000s) and they are quite harsh on the rotors.
My car is at the garage at the moment and they've just fitted 4-pots on mine, and the stock 16" WRX rims fit over them with a reasonable amount of clearance. Worth a try with the BBS mags.
I'm having Pagid Blue pads put on the 4-pots, recommended by Steve at Racebrakes. Not sure what the details are, so will need to read up on them more..