I've had multiple RX7's (all bodies), and have run Hawk and EBC pads on both the track and street.

For your RX7, get the HPS if you are not aggressive, do not go to the track, and are afraid of brake dust.
Get the HP+ if you want better braking and don't mind cleaning your wheels.
Do not get Blacks or Blues. I've run Blacks on the street.

If you have OEM rotors, the heat from the pads will not cause them to crack. Even on track use. I've used Blacks on stock rotors on the track, and they didn't even come close to cracking. PM me if you want a lot of RX7 braking information.