From what I have experienced, you only need the little tool for the rear brakes and can compress the fronts with a C clamp. You can get a little adapter for a 3/8" socket for about $10 at most parts stores. Don't know about Brembo's.
My experience in doing pads and rotors is that you should replace both at the same time. If you only replace the pads, the grooves in the rotor will be transferred to the new pads quickly - maybe not a real problem but any rusty areas won't grab and you will have reduced grab area. If you only replace the rotors, then the grooves in the pads won't contact the new rotor and those non contact areas may rust.