The Wi-Fi Remote, LCD Touch BacPac, and the new Battery BacPac are compatible with the HERO3+ cameras.
You do not need a Wi-Fi BacPac if you have a HERO3+ camera since the HERO3+ camera has built-in Wi-Fi. You will need the Wi-Fi Remote or the GoPro App if you want to use the HERO3+ camera's built-in Wi-Fi though.
The current 3D HERO System is NOT compatible with the HERO3+ camera.
The original LCD BacPac or Battery BacPac, are NOT compatible with the new HERO3+ cameras.