IBP Inventory module

Please share your opinion on IBP Inventory module.

I have come across this below note in help document.

Note : Inventory optimization algorithm only support Period between reviews (PBR) inputs greater than or equal to 1.

1. What is PBR ?

    2. How difference is SAP IBP inventory module from SAP EIO/EIS ?

Do we have more factors considered in IBP Inventory module ?

   3. Where do we have detailed documentation on these 3 algorithms ?

   4. How Safety stock planning calculation happens ?  Do we still have all methods used in APO ?

Thanks